Auto rifle is definitely the most viable primary to use in the crucible.Is the auto rifle the only worthwhile weapon late-game? I swear that 80% of my deaths in Crucible are from a 25+ with an auto rifle.
Scout rifle is a joke. Pulse rifle is meh (haven't used it much). Hand cannons are just okay at best. Can't go wrong with the auto rifle. The weapons need major balancing in PvP IMO.