Okay, a brief summary:
There are 2 G41’s:G41(W), and G41(M). the Mauser G41 was ridiculously over complicated so didn’t work well, and the Walther G41 became the G43 when fitted with a proper gas system. Both of the G41 rifles had the same muzzle trap with annular piston gas system that was completely bonk and was used because the German high command had a prejudice against drilling lateral holes for gas. both of these rifles were never on general issue because, frankly, they were crap, one fundamentally and the other just due to the gas system.
G43: works quite well, but is somewhat fragile in the action which leads to parts breakage. a little complex.
SVT 40: the best designed but the worst made of the three main semiautomatic battle rifles in question. It is let down by its manufacture and its fiddly gas regulator. If it had been made well it would have been really excellent – everything is there in principle , and if it had been made by any of the other major powers it would have been very good.
Garand: the worst designed but the best made of the three. Fundamentally, it is little more than a mechanised turn bolt rifle, rationalised and slimmed down. It is the most accurate and most reliable of the three, and capable of the highest sustained rate of fire – this is little short of amazing given how many weaknesses there are in the design that can lead to slight damage stopping it from working. it also has the most primitive and indeed worst gas system of the big three. But, because American production engineering was the best in the world, it worked and worked very well, and is certainly the best of the three.