In considering arena dominance, you need to look at K/D as well.
Spit V and Seafire II should have the same ENY value. The usage of the Seafire will vary considerable from tour to tour according to which map we get stuck on for weeks.
Also don't forget ground kills. A2G birds like the mossie will have poor K/D ratios because people use them as fighters, or because they're attacking fields a lot. The same goes for the p47. If they're ain't mud on it, it ain't a jug.
Anyway, it's clear that the La7 and the Dora need to be perked. If that happened, you'd see more La5 drivers -- which doesn't have too low an ENY value, its pilots simply prefer the La7.
The G10 needs to go about 18 pps. The zeke is fine at 25 -- I see a lot of them on base defense, so you'd expect them to have a poor K/D showing.
The IIc probably shouldn't be touched as far as ENY rating goes. The IId is ground-attack plane. THe problem with it is that its guns can't penetrate armor, while the armor's guns can knock it out of the sky.
Ki-61 should be boosted a bit.
The 205 doesn't need to be touched. Check out the K/d ratio.