I’d say the US had better bombers overall.
As for fighters, I’d say it’s a toss-up between the Spitfire and the P-51 Mustang. Each had superiority over the other in small ways, both were the best of WWII.
Naturally aspirated P-51, or the modified high altitude verion with a supercharger?
Well its hard to compare sometimes. You can have the best plane in the world but if you have a crappy pilot flying its not much good. Dont forget the British had a 2 year head start on combat flying experience than the Americans did. But just as specs. The Spitfire and P-51 were about on the same level.
True. This is clearly seen in the world of motocross. Real motocross, not the crappy acrobatic stuff it has reduced to by moving it into small stadiums to force people to pay a ticket fee to see it. You could have an inferior bike and still whip the competition. I suppose the pilot is a huge part of the plane like this as well.
It’s difficult to say who made the best planes because for the most part, the US planes had a different mission profile to the UK planes, so would have to be measured by different criteria. There are many breeds of fighter and bomber etc, and like tools in your garage, there’s often a different “best” one for each job. It’s always worth remembering that the USAAF flew Spitfires and the RAF flew Mustangs!
For example - fighters. During the Battle of Britain, the Mustang wasn’t even built (the prototype not flying until late in the year) and American fighters in production at the time were quite frankly woeful. Only the P-40’s were really much cop - and even then in a second rate sense although they did great service in the desert. When the Mustang did become available using the same Allison engine as the P-40, it was something of an underachiever. But Britain needed as many aircraft as it could get. Nevertheless - the Spitfire and Luftwaffe’s Me109 were pretty much the pinnacle of fighter design at the time.
But 1940 didn’t last forever (thank god!) and after the Spitfire and Hurricane triumphed in the Battle of Britain on behalf of the freedom loving peoples of the world, the battle moved from the skies of the South coast of England in daylight. The German’s moved to bombing at night so nightfighters came to the fore. The war in the North African desert heated up. And so on. In other words - the missions changed.
So when the war moved to over Germany, the US fighters really came into their own - particularly with drop tanks! The Mustang, rescued from “average-ness” by Packard built RR Merlin engines, was the right plane at the right time for the later stages of the war. Being able to fly escort right into the heart of Germany was something the Spitfire couldn’t achieve. It was principally an interceptor and did the job very well - and would be a ferocious opponent for the Luftwaffe wherever it could reach over Europe - but by 1943,44,45 a long range escort was also needed. The fighter you would want for fighting the enemy over your own country isn’t necessarily the same fighter you’d want to fight the enemy over HIS!
The same applies for bombers. If you want to drop an awful lot of bombs on the target, you probably couldn’t beat the Lancaster until late in the war with the B-29’s. The B-17’s maximum bomb load was pitiful next to the monster loads a Lanc could take. But whether flying by night or day, I would contend that the US bombers were excellent aircraft which compromised bomb load severely for defensive abilities (which ultimately weren’t enough anyway). To keep losses down to acceptable levels B-17’s and B-24’s HAD to be escorted to their targets - the RAF’s bombers did not - a consequence of using the night instead of heavier defensive armaments. With regards to precision bombing - again this is tactics. But on a technical level, the RAF showed the Lancaster in particular to be capable of outrageously good precision bombing.
As for the Mosquito - there are some people who suggest that it would have been far more economical to build fewer big four engined bombers and more Mosquitos. The Mosquito had a far, far smaller crew, and could carry a very substantial bomb load all the way to Berlin. In fact the USAAF’s B-17’s were allegedly capable of carrying a smaller bomb load to than Mosquitos could. Bomber versions carried no guns - flying fast enough to evade interception. And if one went down - 2 men dead. If a B-17 went down - 10 men dead. A Lancaster - 7 or 8. Given the severe man power problems Bomber Command was facing, the Mosquito would seem quite an economic alternative to four engined heavies. But Bomber Command was sticking by it’s heavies for better or worse.
What makes the Mosquito still more special is it’s versatility - it could be put to use for almost anything and be succesful. And best of all - it used little strategic materials - a huge benefit for besieged Britain. Off the top of my head, I can’t think of a single WWII aircraft from the US that can claim the excellence across many “trades” that the Mozzie can. Not to diminish the achievements of the superb aero-engineers in the US, some of whom I count among my personal “heros” - but aircraft as special as the Mosquito are rare indeed, even in the UK.
But then, nor did the UK produce a single seat fighter that achieved near dominance over German skies. I don’t believe it is a matter of pure weight of numbers - the P-51 was a class act in terms of technical achievement, partly due to the genius of the gentlemen at North American in the US for cramming so much bloody tankage in there, partly due to the genius of the gentlemen at Rolls-Royce in the UK for designing the peerless Merlin.
Honorable mentions must also go to the less glamorous aircraft of the war: for the UK the likes of the Bristols like the Beaufighter, Blenheim etc and the Hawkers: the Hurricane, Typhoon, Tempest and so on. For the US, the P-47 in particular was a work horse that got far less credit than it was due. The B-25’s and B-26’s - excellent medium bombers. The list could go on forever.
All that said - because “best” is really defined in terms of mission, and the missions are frequently different enough to make comparison fruitless, it’s hard to say who made the best aircraft.
EDIT: I think I can be more specific than that. The best aircraft (plural) of WWII - anything with enough RR Merlins!
Damn good post Festamus, it is a difficult question and one which really does need qualification.
I’m a huge fan of the P-51 myself, but if we’re going purely on aesthetics my vote would have to lie amongst the Spits.
I second the motion on Spitfire by aesthetics. There are few better sights in this world than the classic image of a Spitfire framed by the Kent countryside.
Having thought about this too much, I’m off outside to listen to ‘Land of Hope and Glory’, holding a gin and tonic with a Union Flag wafting in the breeze, my bottom lip quivering slightly whilst the upper lip remains stiff in the finest colonial tradition.
Now now. You’re just straight wrong.
Pimms and Lemonade puh-lease! 
I third the statement that the Spitfire was a better fighter for dogfighting and the Mustang as interceptor. I don’t know what a Pimm is but if you’re passing them around, I make a mean batch of home-made peanut butter cookies!
I think the only real flaw that the Spitfire had was it’s gravity based carburetor, which gave it a bit of a dissadvantage as a machine against the fuel inected German fighters. This gave the Germans the ability to use altitude to their advantage, for one thing. Despite this, the Spitfire pilots proved the worth of their planes and themselves as pilots.
That disadvantage was fixed by 1941, when Rolls Royce introduced a diagphram into the carbouretter to stop the fuel cutting out in neg-g dives (after battle experience from the Battle of Britain filtered through).
The Spitfire (IMO) was the best interceptor (short range fighter) of the war, the Mustang probably the best escort (long range fighter).
I am glad to see many very very good posts here, most notably from festamus. It is a good point to say that the Spitfire and the P-51, had very different roles in combat. The Spitfire is labeled as a “Single-Seat Interceptor Fighter” , and the P-51 Mustang as a " Long-Range Single-Seat Escort Fighter". When comparing the Spitfire and P-51, I would have to put my vote for the Spitfire, becasue I feel that if the two would meet, the Spitfire would be the winner.
The Mosquito is the best “all rounder” plane during WWII, capable of taking various roles. It was used considerably as a photographic reconnaissance craft, and also led the way for the Lancasters as it dropped flares to indicate the precise target. It was also a fighter bomber, and anti-shipping strike aircraft. With a maximum speed of 408m.p.h. it was faster than most enemy fighters.
The Lancaster was a great heavy bomber, and it is very hard to decide which country had the best bombers. It could carry the most load of any bomber during the war, and was also considerably accurate, more so than the American bombers. The downside of the Lancaster was its speed and it had a low altitude. The Lancaster I believe had better technology on board, incorporating Radar in most of it. It could easily calculate where it was and the Lancaster could be used as an all weather bomber, due to targeting technology onboard.
For fighter I would say the British with the Hawker Tempest V/VI. Depending on the model, a Spitfire typically had about 1,500 horse power, while the Tempest had 2,260 horse power. Not only that, but its armament was comprised of four twenty millimetre cannons (I believe they were Hispano). Even if it carried bombs/extra fuel/rockets, the handling was hardly interfered with. It had a climbing rate of 4,700 f/m and a max speed of 435 mph at 17,000 feet. Only drawback was that its range was about 740 miles.
For a ground attack plane I would say the Republic P-47D. In an air museum in Ohio, there is a statue giving tribute to the P-47, and giving it the record of allied plane with most overall kill (air, land, and sea). Most people say the P-47 is much slower than the P-51, but really the P-47’s speed is 426 mph and the P-51’s is 437, a difference of 11 mph. The P-47 had eight fifty calibre Browning machine guns, instead of six that most other American planes carried. Nothing could out dive it, and it could carry quite a powerful payload. And eventually it was fitted with a bubble canopy.
Interesting that you say the Tempest. It did destroy more V-1s than any other R.A.F. Fighter, over 600, though I must correct you on the Hawkers Specs. My sources say differently from your sources and, and another reliable source states the same. The Hawker Tempest had a 2,180hp Napier Sabre II. Max. speed was 426 m.p.h. It is true that it had four 20mm Hispano cannons.
It was a great fighter, though I would say the Spitfire was still better. I would like to say that when comparing the Spitfire with other planes, it is advisable to compare it with the Griffon Spitfire. Came out early 1944, around the same time as the Tempest and P-51D Mustang. The Spitfire was deffinetely not underpowered, or under armed. It had a 2,035hp. RR Griffon 65 engine. Max speed was 448m.p.h. It had an armament similar to the Tempest yet it could carry rocket projectiles. Four 20mm Hispano Cannon, 1,000lb in bombs or rocket projectiles.
More spouting on this subject if I may?
I’ve seen elsewhere (probably the Best Bomber thread!) an argument about whether the B-29 was better than the Lancaster, and it’s kind of inspired me to write this.
Something to be wary of when judging “the best” WWII aircraft of any particular type, other than subtly different missions as discussed earlier (e.g. interceptor vs. escort) is that the aircraft appearing late in the war were half a generation ahead of those used at the start of the war.
Perhaps this is a “well DUH!” moment but the implications are worthy of note. Compare the Lancaster to Bomber Command’s other aircraft. Constructed in a similar fashion, with piston engines. Bigger and better for sure, but no different in principle. Sure, it could carry some snazzy avionics like H2S and Gee, but it was very much an aircraft of it’s generation. The B-29 on the other hand, had one foot in the “existing” generation and another in the next. While still powered by props, it was pressurized. It was very much set apart from the other four prop heavies which saw major service in the war. Even withstanding the accuracy problems of flying higher and faster, the B-29 is without doubt a “better” bomber on a technical level. But it all comes down to the right plane at the right time.
The designs fighting in the first half of the war were, generally speaking, 1930’s designs using 1930’s technology, with whatever 1940’s “must-haves” possible tacked on. For example - the Spitfire was intended to carry several .303’s (and it is fitting these in that makes the wing the shape it is, apparently - despite the elliptical shape being very good aerodynamically) yet it became clear that these alone were not adequate… prompting them to shoehorn 20mm cannon in there!
Which brings us to the likes of the Tempest. The Tempest (and the Fury which sprang from it for the FAA) was perhaps the pinnacle of British single-piston design in WWII - and design moved fast in the 1940’s. People like Sydney Camm at Hawker would be working on the replacement for an aircraft before it had even entered combat. And funnily enough - the Tempest wing was elliptical for similar reasons to the Spitfire wing - to fit guns in - although in this instance 20mm Hispano’s from the outset!
Despite it’s awesome performance - particularly at low leve - I can’t bring myself to consider the Tempest the “best”. By that stage, fighter design was very much evolutionary rather than revolutionary. When the Spitfire and Hurricane were introduced, the aircraft they replaced where of a different age - an entirely different generation. The Tempest was a great aircraft but brought nothing “new” to the party - beyond low level performance lending the ability to chase down V-1’s and Me-262’s recovering to their airfields. I’d say it’s predecessor - the Typhoon, was more worthy of “best” in so far as it’s success snatched from the jaws of failure.
The Typhoon was originally intended as an interceptor to replace the Hurricane (plenty of evidence of the Hawker Hurricane DNA in the wing if you ask me!) and much of the design was positively “old hat” by the time the war started. Look at the Spitfire: it looks crafted lovingly by an aerodynamicist or somesuch… look at a Tiffy, it looks built by a structural engineer with the bits he had left over from the last bridge he did.
It took them some time to get the Tiffy right, and it became clear very quickly after first flight that they certainly didn’t have a good interceptor on their hands. Once all the problems had been worked out, it was quite clear that the Tiffy was good for something… Nay. GREAT for something. While poor time to climb made it a poor interceptor (although perfectly able to handle itself in a ruck with the Luftwaffe), at low level it had all the cards - bag-loads of horsepower, a nice strong wing for hanging bombs and rockets off. And the somewhat dated construction probably loaned it a good deal of resilience to damage. So what better to do with the thing than… beating up the Wehrmacht! The Tiffy became a prolific fighter-bomber - the archetypal image of it being one of a Typhoon unleashing it’s rockets on German armoured columns. For mid-1944 this was just the ticket, for obvious reasons!
So for me, the Typhoon sits firmly in the “best single-seat fighter bomber” while the Tempest that followed it was bound to be “better”, being an evolution of the Tiffy. But it can’t capture the best fighter bomber spot for me, nor can it the best interceptor spot - which belongs to the Spitfire for sure.
For the US, the counterpart to the Typhoon was almost certainly the P-47. Many of the same qualities as the Typhoon. HEFTY construction. I mean, crikey! As a kid, I was always amazed something so fat could fly, yet alone mix it with the 109’s and 190’s and win. Great for beating up ground targets and able to absorb so much punishment. And hey… as fat aircraft go, it’s a looker.
I got some great snaps of many of the aircraft mentioned in this thread, at Hendon last summer. Well, they would have been great snaps if it weren’t for the horrid lighting in the museum! Too much hand-shake for such long exposure times. 
I might see if I can post some of the passable ones up if I can find free image hosting.
In addition, I urge all of you to visit RAF Museum Hendon, and IWM Duxford if you’re ever in England! And be sure to donate generously and bankrupt yourselves in the gift shops!
The only downside being they ruined the looks!!!