I favour the M16 with Red dot sight. Probably one of the most useful weapons in the game (slightly overpowered too).
But the Shotguns are surprisingly good. I didn't bother to use any until about 4 months after I got into multiplayer where I realised the only way I was going to level up faster was by getting the points for all the weapons and I started out using the shotgun only on 2 maps (I forgot their names, but the smallest map and the map with 2 solid areas, outdoor and indoor and the indoor part has the little roofless square where most of action in HQ tends to happen, and it has that dinky little shed in one of the corners). But then I started using the overkill perk and it is a very good weapon if teamed up with a mid-long range weapon, or even on it's own if you know how to sneak around.







