Better balancing of the Apache/littlebird.
As soon as you are able to fly the helicopters reasonably well they are too easy to keep in the air permanently. All you need to do is use flares then fly out of range until flares reappear, and potentially get a quick repair from a passenger or by landing in your own HQ.
Reducing how quickly flares reappear, increasing the talon range, dropping them down to single hit talon kills, removing the ability to repair helicopters, allowing rifles to take them down with say 40 hits, would all help to reduce how overpowered they are. If there's a semi decent pilot you either have to accept getting killed every 2 minutes from a helicopter, or dedicate your whole game to staring at the sky with a talon just to give your team some breathing room.
I've tried that flying technique a couple of times, and can easily keep one in the air and rack up kills until I get bored, and I wouldn't class myself as a particularly skilled pilot. It doesn't feel very balanced to have 1-2 vehicles that are so easy to dominate a game with.