I gotta say KI61. Bit of a pain to get Alt but once up and running it's right nasty. Keep it fast shoot close (200) and freakin don't turn fight a spit unless you know it insideout:aok
P47's all of them are great perk earners. Zoomy like tactics but drop 1 or 2 flaps and a P51 (second step up from LA7driver) is owned.
p.s don't take the hvy gun pack.
Hurri 1 convergence 200 or 225 on all guns. When them hvy's come of CV's sneak right in and "pop" their tails off from 200. A 1.5 second maintained hit takes anything out. Also the "hot shot duelist" A6m is owned.
In general all early planes earn great perkies. Most will teach you T&B (turn and burn).
When your side is out numbered just about any plane will earn perkies but whack a P51 or a gay err LA7 with a KI61 p47D11 and your looking at 7 to 15 perkies per kill, if you land.