It shows that 3arc at least got something right in that there is no MW3 ACR or MP7 that just outclassed everything. The guns that came close to being 'OP' or dominant, however you look at it, were nerfed, and rightly so. I like how much variety there is, though the M27 seems to rule HC due to it's non existent recoil and long range accuracy.
It really depends on what weapons you are playing against. Since I always seem to be playing teams with 6 SMG users I need to have a weapon to combat the fact that they can win from anywhere.
I prefered the original FAL with select fire. After all the nerfing I now prefer the Peacekeeper, It is by far my go to weapon because it is so flexible.
Runer up would be the AN-94.