That would be a good WWF matchup. Put a shotgun and a pistol in a ring let them fight. Guns shoot themselves right? Rosie can ref.
J/K. Indoors I would certainly go with a pistol, in a substantial caliber. I think shutguns are too heavy and bulky, compared to pistols. In a street environment, I would say a shotgun and pistol are about equal. Pistols generally have higher capacity and faster aim. Shotguns can do mre damage and hit multiple targets, depending on ammo. At long range, I would go with a long barreled pistol, like my .50. I can get 2" groups at 100 yards with some of the 300 gr ammo. From what I have seen of the ballistics tables, It should easily take out man sized targets at 300 yards.