Easy!
The Mig-3, one of the most overlooked planes of the war. If only Russia used them as intended. Then again Germany didn't have high altitude bombers or fighters...
Fw 190 family, but the Dora 13 is my favourite! The Ta-152 and 154 are also nice birds as well as the whole Bf 109C/D/E/F family, the G's are way over done today.
And of the course, the Fokker D VIII. Way advanced for it's day. Too bad it had such a undeservedly bad reputation.
Other planes I can't get enough of:
Yak-3
LaGG-3
La-7
P-39
Fokker D VII
IL-10
Ho 229
F-86
P-80
Bf 110
Ju 87