I've tried my hand at using both a shotgun and a sniper, whose primary catch is that they have extremely low TTKs, but so far, using either is absolutely pointless. Sniping with an AR is by far the better choice. WHy even bother? Using either does you no favors in this game.
but see there you are wrong. ive been using some snipers and i am loving it. havent tried my hand at the shotguns yet but it just takes a game or two with a good sniper set-up and learning the sniper routes on the maps to be able to do well!