Chopper swarms need to be nerfed.
Low alt and stationary choppers should be extra vulnerable to ground vehicles and infantry, or automatically sway around in flight to avoid getting hit, but lose accuracy in doing so.
High alt attack choppers should get hit by normal AA. With a toggle on AA to decide whether to target helicopters or planes only so people cant spam them as meat sead.

Or easiest change of all, put them on limited fuel like planes so they cant be parked on the map indefinitely.