I don't know if I agree that the N1K2, Spit, and La7 are amoung the easiest kills in AH for me. Flown properly, they are amoung the hardest planes to kill- period. This is from my perspective in a 109 or 190 though. The N1K2 will outturn anything but a 109E4 (and it can turn with that), it will outaccelerate anything but the D9 and G10 (about on par with those), it has great firepower, climbs and dives well, and it is as just about as fast as the LW planes except the 109G10 and the 190D9.
Spit9 is in the same book as the N1K2, but it isnt as fast.
La7 is the true D9 and G10 killer. It simply does everything better, literally. The earlier 109s can outturn it though.
The 'trick' to killing them is to simply come in with an advantage. Oh, and to know your plane better than he knows his.
A great pilot in a 109G10 will kick an average pilots ass, even if he is in an La7. This is because the G10 pilot can get more out of his plane than the La7 pilot can, even though the La7 is capable out outperforming the 109G-10. If an average pilot in a 109G-10 meets a great pilot in an La7, he can kiss his bellybutton goodbye.