The sniper.

[Benson]

...
When a clan start using it he's stronger, you can take BoB/FD as exemples. A lot of players will say "hey they are progressing, the AR is for nothing" but it's false, how many CM did i play against them on the 1.0 and before they took the AR...

BoB and FD did progress a lot, though you're right in a way. What helps them most is the ability of the AR to use the recoil as accelerator (riflejump). As the AR has 20 bullets in 1.1. riflejumping got so popular.

If you're using a sniper in CTF and you lose a duel against an AR, who enters your base (he can have 4 hp and still...) and riflejumps away with the flag around the next corner, you're not able to get him.
On maps like depot (e.g. your mate is tunnel, riflejumper is main), that's a save flag for them.

--> AR isn't only the strongest fragging-gun, but also the strongest tactical (ctf,htf,tktf...)-gun.
give the AR just 15 bullets again, and it will be better. (ofc it's still possible to riflejump, but it's that strong for fragging, so less people will use it, and the game will be more balanced.)