There is only one fighter harder to do well in than all others, in my opinion: the P-40.
Now, in a scenario environment, where you are in many on many against the historical plane set (in this case A6M2), the P-40 is nice. But in the MA, I think it's the hardest plane.
I think F4F's, P-39D's, and A6M2's are all decent. Worse, in my opinion, are C.202's (but only because guns are so very weak), Spit I's, Hurri I's, Bf 109E's, and Bf 110C's -- but you can still kill OK in those if you use their strengths.