I dont think m16 is overpowered, and no i do not use it myself. The M16 is just reeeally good at the thing it should be doing, medium/long range. At close the m16 is almost useless and no match for other assualt rifles (except for m14,g3,g36c) or smg's, i really dont get the m16 hate here. The gun that you should be hating is ak47, it has overpowered damage, is full auto and good at all ranges. Guns next in line after the ak47 are mp5 and ak74.
I also dont get the hate for some of the perks, juggernaut, stopping power, uav jammer, are all counterable perks and not really overpowered. These perks work for most guns and are most used but dont have to be game breaking.
Marty,3xgrenates,noobtube are cod's worst flaw.