5) Fokker Dr.I
Manfred fricken Richthofen scored his last kills in one. Painted red. If that's not cool enough for you, go find another hobby.
4) Boeing B-17 Flying Fortress
Yeah, other planes have served longer or dropped more bombs or been more common, but the B-17 will forever remain the symbol of the first strategic air campaign. You tell some guy who had his wounded carcass dragged out of one that brought him safely home after having both wings and the tail shot off that it's not the greatest airplane ever...
3) Fairchild A-10
Strap wings to a cannon and watch it fly.
2) Curtis P-6E Hawk
The best looking biplane fighter ever built... Heck, it's a contender for the best looking plane ever built. If truth = beauty and beauty = truth, this was the truest thing with two wings ever made by mankind.
The next is a tough one... What to put in the #1 slot when there are so many worthy candidates? We'll try, though...
1) Hawker Sea Fury
Okay, this one is the best looking piston engine fighter ever. Clean, slim fuselage. Graceful elliptical wing. Shot down jet-engined MIGs over Korea. Dreadnought still wins air races. Makes the heart race just to look at...