Axis wins in my opinion. Numero uno, the Fw-189 followed by Arado 234B and the Blohm and Voss 138 (Flying Clog). Weird and interesting one and all. On the Yank side, the Piper L-4 Grasshopper - you don't get any more simple and graceful with a 65 hp Continental 4 cylinder air-cooled powerplant, all weighing in at 1,200 lbs.
Martins B-26 Marauder is high on my list, though I have a warm spot for Locheeds P-38 probably since I was lucky enouth to ride in one many years ago.