ACR, MP7, and PP90 are the best guns in this game.
Marksman (Pretty useless perk IMO unless you can't see good. It's a big mistake using this perk and getting used to it, because:
you'll be concentrating on one player with a name tag instead of your surroundings where an assassin can be.) Overkill is pretty useless.
Best Class for KDR & killstreaks wh%$rs:
or Attachments w/ Ext. Mags & Silencer
or Reaper < AC-130 < Juggernaut (2 hit kill cqc)
Fast Reaper set up: (Perfect for Village)
Most reapers I have called in a game was 5 with this class.
Fast KS Class
My PSN is xlx-missile-xlx add me, I'm on everyday (geez what a low life)