Alot of people say that the shotgun is the best HD firearm. How many home invasion BG's do you think could survive a blast from a 12ga with buckshot at point blank range?
For range time usage, the shotgun is the most versatile. Slug barrel for deer hunting. Smooth bore for HD, bird hunting, trap, skeet and sporting clays. What more range uses are there?
If you want to shoot paper targets and occasionally hunt coyotes or prairie dogs, the AR-15 223 Rem is hard to beat. I have an AR and its definitely not my first choice for HD. Single bullets must be placed accurately to be effective. In a SHTF scenario, I want all the lead I can throw at one time.
My vote is the Remington 1100 3" magnum and have 2 barrels. One rifled slug barrel and 1 smooth bore 28" with remchokes. Bird shot and buckshot can be fired through a rifled barrel without issue for HD.
My HD shotgun is a Remington 1100SP 3" Mag with a rifled barrel, its also my deer gun. Yes, its only 5 shots but how many do you need? I load mine with slugs and 00 buck for HD. Sabot slugs for deer.