Most of the planes are very good. It's what you decide to use it for that makes it best for you.
Best all arounder might be the F4U's or 38's
I prefer the F6's or P51-B over them because I haven't figured out how to fly them yet. Rockets and bombs are a favorite of mine.
Turn and burn might be the spits for sure but those Ki's are very nice
B&Z'ers would be 51-D, 190D/8 and 109's none of which I fly well
Most fun would be LA7-5, FM2, F4F, 110, 109f, Mossie
Most hated on my 6 Spit 16
And the one that makes my heart race the most.... A goon

I get a few kills a month in them