I would think German weapons of WW1 & 2 are so popular because they created weapons that were the first of their kind. Not THE best, but the first. The Germans were the first with chemical weapons, jet aircraft (which was the He 178 in 1939, and and no Allied had a more reliable jet engine before then), long-range rockets, assault rifles, battleships, and also to have the largest artillery, powerful tanks, and not to forget the possibilities of aircraft carriers (which were not completed by the end of the war) and the rumors of nuclear weapons.
If it wasn't for a series of factors that played a part on both sides, these weapons would've played a bigger part and the war would've had a different outcome.