Favorite plane . . . hmm.
Here's the problem: favorite for what? For example, there are planes I fly the most, which I like, but my reasons for flying them include my weird preference for flying planes with higher ENY values.
For me, an easier thing to say is what plane I fly most frequently, or if you were flying in WWII and could pick the plane you flew, what would you pick, etc.
The planes I fly most frequently are the F4U-1 and the P-47D-11. (I'm working on perhaps the P-38G, but I hate the darkened view through the front glass.)
The non-perk plane I'd pick if I had to fly it in a real WWII-style war (if it flew like they do here) would be the P-47N or P-51D.
The plane I like for most fun to fly just for angles fighting is probably the Spit V or the A6M5.