Chalk me down with Joker2 as annoyance rather than fear:
Tempests - Because they always hover around 20-25k and run at the first sign of a co-alt con. If they can't pick it from a 10k alt advantage they won't fight. Most over-inflated K/D of any plane in the game.
262s, probably the MOST annoying and for much the same reason as above. IMO they should be restricted to the HQ base with the 163. MAYBE I'll give them the Zone base for strat targets, as well, but they shouldn't be available at every field.
P-51s - A lesser annoyance, but again, for much the same reason as the Tempests.
Ok, there IS one plane I fear: A B-17 with 999000 manning the guns.