Gotta be the A-26 (or was it the F-26?) Invader. You wanta see a porked game, just put that baby in. Good bomb load, too fast to catch, manuevers like a fighter, and, if they're stupid enough to put the gun nose in it, kills anything unfortunate enough to find itself at 12 o'clock.
Toss in the 4x50 turret guns, and kiss your suspension of disbelief goodbye. You'll never see another type of medium buff in the arena once the A-26 shows up (at least not without an RPS you won't).
B-26, A-20, He-111, all good choices. A-26? Just say no.
--jedi