I'm afraid you'll have to qualify your initial question, "Who built the best fighter planes in WWII?" with, "who built the best offensive and defensive fighter planes in WWII..."
If I had to defend a small region of airspace over my own country (with Expert pilots) I'd agree, give me a 262. If I had to fly 800 MILES to get to the fight and return for months on end (with an average collection of pilots) , you'd have to give the nod to the P-51Ds and P-47s (especially the Hot Rod M's and N's).
Just my $.01. I'm saving the other penny.
langerl