In playing around with the guns, I would probably say the full auto-ARs are the best. The KN (looks like an AK sorta) has extremely little recoil and shoots pretty straight...somewhat slower rate of fire, but it is a 7.62 weapon. Maddox is ok and mostly suited for close/medium range...5.56, high rate of fire. Rampart fully kitted out is decent.
For snipers, forget the DMRs. The paladin/keshka or w/e are ok but very low ROF (but if you hit you do a fuckton of damage), Outlaw is a good alternative: little lower damage, but it is bolt action but a much higher rate of fire.
Pump shotty (MOG) is still best bet for very close range. It can 1-shot level 3 armor if you're close enough. Fully kitted Cordite (the p90) is also pretty good at very close ranges due to its insane ROF.