OT: M9 (There is no doubt here.) and the Uzi isn't half bad if you're trolling people on Alaska. I get kicked after three kills though, so I still wouldn't recommend it. Under-powered shotguns (Spas-12, etc.), and the FAMAS, unless you like the FAMAS like me.
M700 is a great sniper, I agree.
To be honest, I would not recommend M14, M4 Patriot, M4 Iron Beast, or any extremely OP shit like that.
It's funner when you use less OP guns, greater sense of achievement and people commend you.