First off, I must have at least twenty different answers to the many variations of this question!
After giving the matter some serious thought, as a military historian, I would have to say, my favorite WW2 aircraft would be the Douglas C-47 Skytrain that hauled the beans, bullets, & bast*rds w/parachutes that made everything else possible.
I kind of surprised myself with this answer after reading so many books about the “Jugernaught” P-47 Thunderbolts and “Whistling Death” F-4U Corsairs.
I’m certain that this isn’t the sexiest answer, and a lot of people here might be groaning now, but I feel that the C-47 in doing it’s job, made more of an impact than any other aircraft in WW2 for the allies.
And remember, General George S. Patton, a serious TANK expert, said the same thing about the 2-1/2 ton truck!
I’d love to “discuss” all of the different variables included in this question. Such as Fighter, Bomber, American, German, most effective, most feared, fastest, etc., etc, etc.