If you want to look cool....and be dead after the fight, get an AR-15.
If you want to finish an intruder and have your neighbors thank you, get a shotgun. Short a barrell as possible so you don't catch it on lamps, your wifes head, on curtains or anything else that is in the room when you draw bead on someone. Also, remember, there is nothing more ominous than the rachet clack of a shotgun slide in the dark.