To me it depends on what you are playing and what you are trying to do. if you are playing CTF and are on defense you should probably use an assult rifle my choice would have to be the Commando. if
you are trying to get the flag I would use a sub machine gun and so on
I find the Mpl with rapid fire to be useful for a run and gun cause it has high rate of fire and is pretty accurate, but you would have 2 run scavenger, sleight of hand, and marathon.