Might as well get the first one started now, no point waiting:
P-51D Mustang vs Commonwealth Boomerang II (Australia)
P-51D Mustang

Engine: 1,490hp Packard/Rolls Royce Merlin V V-12
Max Speed: 437mph (704 km/h)
Climb: 30000ft (9145m) in 13 minutes
Service Ceiling: 41900ft (12770m)
Maximum Range: 2,080 miles (3347km)
Weapons: 6x 12.7mm (0.5in) MGs in wings
Up to 2,000lb (908kg) of bombs or 6x 127mm (5in) rockets
First designed to a British specification (NA-73) for a long range escort fighter, the first Mustangs (MkIA) were rejected by the USAAF, although they were adopted in a close support role by the RAF. The British replaced the Packard engine, which they found underpowered, with the Rolls Royce Merlin which was already in widespread RAF service. They found this significantly increased the Mustang’s performance. The USAAF finally adopted the aircraft and both found it ideal for escorting the long range daylight bombing raids over Germany.
Commonwealth Boomerang II

Engine: 1200hp Pratt & Whitney Twin Wasp
Max Speed: 296mph (464km/h)
Climb:
Service Ceiling: 29000ft (8845m)
Maximum Range: 930 (1490km)
Weapons: 2x 20mm Cannon and 4x 7.7mm (0.303in) MGs in wings
In 1942, the Australians found themselves on the front line against Japan with only a few American Brewster Buffalo fighters, which were soon outclassed by the Zero fighters of the Japanese Navy. In desperation the Australians asked Commonwealth Aircraft Corporation to produce a stop gap fighter based on the North American Trainer series which Aussie pilots were trained on. The CA-12 Boomerang was like most things Australian: Tough, with no frills…but it worked. It was outstandingly maneuverable, and was in no way whatsoever outclassed by its Japanese enemies. The Boomerang never carried bombs, but it did mark targets for “heavies”. The Boomerang also carried out close support with its guns. The Boomerang was possibly the most successful stop-gap measure in history. It certainly proved its worth, for the Japanese never looked down their noses at the tough Boomerang. Production ceased in early 1944.
You’ve got until tomorrow evening (Brit time - roughly 35 hours from now) to get your votes in
ONE LINE ANSWERS WILL BE IGNORED - JUSTIFY YOUR OPINION!