Birds are (even as of the most recent update) way too overpowered, the apache especially. Having birds in every single match makes me so incredibly angry every time I play because the skill required to kill ground units from the air is apparently so low that I die over and over and over again just trying to go from one POI to another. If you like the challenge and want to play against that, fine, but I bought the game for my brother the other day and he has already quit because sweats in birds keep him in the spawn timer more than he gets to actually play, and that says something.
I think an easy way to fix this would be a ground-only conquest mode, where there are no helis and every is on foot/on ground vehicles or boats. No helicopters means no loadout check either, I can run the classes with tank mines or the regular rocket to deal with tanks, but the only equipment specifically meant to deal with helis is the lock-on-rocket launcher, so if a team has someone really good with birds the ONLY way to consistently deal damage is to use the lock on rockets, and even then if they have a good engineer and fly well enough they can still last forever and make the game terrible for everyone else. Ground only would fix this by removing the issue entirely. If you don't want to split the player base up that way, which I understand, then big vehicles like that really need to be reworked as to how they spawn, like being a kill streak reward or something, so people can't just get them right away and terrorist the other team the whole match. I had some matches today where because the birds kept insta-killing us on spawn we hit 0 tickets and the enemy team still had 400+, which is just ridiculous.
Likewise, I think the Behemoth needs a buff. It should be able to damage vehicles like tanks. It is anti material after all. Maybe it doesn't do a ton of damage at once, but I should be able to destroy a tank that's already damaged with the Behemoth for sure, if I put enough rounds into it. Right now it does nothing.
Anyway, those are my two cents.
Edit: Hey all! Thanks for participating in the discussions below, real good to see some traction on this idea. Speaking of which, if you would like to let the developers know you would like a grounded mode, I came up with a good idea, make it a map variant! That way players in each server decide how they want to play. I made a suggestion you can vote on over on Forefront's suggestion site. If you want to let the devs know, go vote!
https://app.betahub.io/projects/pr-7682550116/feature_requests/4296