MP40, Browning and Stopping Power, Stopping Power is all I use aside from Double Tap on the STG.
The Browning is just cool because you can blast people's limbs off.
i like the mp 40 all around because of how lil recoil it has and its really powerfull with stopping power. i pretty much only use stopping power unless in hardcore. the stg-44 is also another favorite of mine cuz its still powerfull and acurate with the silencer on it so i use that on small maps, and the mp-40 any other time (unless im snipping)