I feel like weapons are hard in this game. Here's the problems with the primaries that I have(not including secret ones):

RK-44: All-round great, and that's the problem. No downsides found.

Eagle: Insta kill from mid range? Massive damage from long range? Shotgun? No. Stop.

Defender: Not great because of it's projectiles. Not fair at times, since you can't really avoid it. Can be countered easily, though, making it unfun to play as and against.

"The rest:" not really worth using. eh.