The attack boats are pretty damn fun. I joined late into a round and got 9,000 points from just boating and unlocked nearly 1/2 of the total unlocks for it.
Also, they are called power weapons for a reason. The USAS12 isn't that great, but those sniper rifles, with the right position, you should be able to pick up at least 10 kills.
That brings me onto normal, non-power sniper rifles. They are all pretty damn good. Since if you hit someone and someone else kills them you still get credit for the kill, which makes getting "kills" much easier.
Carbines are great, and all class so a support with the ARW is pretty damn effective and you're not constantly running out of ammo (I'm finding supports to be the least used class ATM)
Hopefully tonight I get a few more unlocks cause right now I have the first shot gun, 2 carbines, 2 snipers unlocked, 2 PDWs, and 2 assault rifles. I picked up and AEK, but didn't get to hang onto it long. It still seemed like the ACW is the best weapon in the game (it seemed like it was in beta or the AK 5C)