any combo weapons will work and have their advantages but my favorite set up is:

ACR with silencer and either noob tube or red dot depending on map
P2000 with silencer and red dot
Claymore, unless you are playing with people that use shields, then I use semtex.
Perk 1: stopping power or slight of hand
Perk 2: cold blooded
Perk 3: Sit rep