i prefer either a .50 caliber or a .44 caliber round. damage tops rate of fire, only meatheads pick machine guns because of there in ability to aim, sneaky bastards use rifles and camo to survive, an AR is alright and an all round weapon, an SMG is for those speedy bastards on the map and a shotgun just pisses you off around corners. they all have pro's and con's, EG: damage tops RoF in MW2 while RoF tops damage in BlOps.
And off topic but comon treyarch make a map where a sniper is useful, the maps are all set out so theres a maximum of 2 good sniping positions on them, i think the dev team have a grudge against snipers. all of the maps are to clustered and action packed theres no moment of peace and no real free movement choice, no more run and hide in the field somewhere, its just "FOLLOW THE CORRIDORS, NO FREEDOM ON THESE MAPS" thats something they can fix.
And just no claiming hacks anymore guys, 99.99999% of the time its your connection that kills you alright, quit bitching about hackers