Personally, the only vehicle I feel is really ridiculous is the stealth chopper that is able to drop bombs while in stealth. That is just ridiculous. It flies in, drops bombs, then flies away to replenish the bombs, completely safe with literally no way to lock on any rocket. Then it comes back and does it again. I played a game yesterday where the top player on the opposite team just flew this helicopter for an entire round. No one could get near him with anything. Just stupid.
A luck shot by Lis, or maybe a wildcat that is close enough might be able to give it some problems, but otherwise it is pretty much invincible with a good pilot