I have 6 favorites in no particular order:
Curtiss P-40. Nothing says WWII quite like it.
Supermarine Spitfire. Most elegant aircraft design of WWII
Messerschmidt BF 109. Willi's lil fighter just looks so damn cool
North American Mustang. The plane just drips victory
Grumman Wildcat. Rolli-polley fighter that was tough when we needed it
Mitsubishi Zero. Japan's wonder fighter that seemed unbeatable.
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Honorable mentions:
Lockheed Lightning
Chance Vought Corsair
Grumman Hellcat
Boeing B 17
Focke wulf FW 190
Junkers Stuka
Lavochkin LA 7
Macchi MC 202 Folgore
Hawker Hurricane
I do so love those WWII planes!