Some AR15 alternatives/Home defense weapons that I recommend.
Indoors use
any pump action shotgun will do, single barrel and double barreled version will do
Rural areas the Mini-14, can fire the same ammunition as an AR15(.223 and 5.56 if specified). As well as us AR mags.
Bear country/alpine
M1A 7.62x51mm
Model 1894C .357 Magnum