The game has been out for several months now, so I'm sure many of you have created effective abominations that you enjoy. So let's share them!
QBB LSW with Stock, Rapid Fire and Quickdraw
Lightweight and Flak Jacket
Dexterity and Tac Mask
This class is designed to abuse the fact that the QBB has one of the highest DPS in the game, strengthen its strengths and attempt to cover its weaknesses. Also, rapid fire is just hillarious on this and the Skorpion.
I also like this class
Executioner with Suppressor and Fast Mags
Knife (Kawaii camo or Bacon Camo is a must on this)
Ghost and Flak Jacket
Concussion (Can be replaced with whatever you wish)
Suprisingly effective for some bizzare reason. Just don't run out into the open