I think it’s best to have all three:
1911
870
AR-15
And lots and lots and lots of ammo.
These will cover any home defense situation you may find yourself in, from home invasion to SHTF.
I agree completely. I'm a big fan of the 1911 for close quarters (although I personally prefer the Glock, it's not something I recommend to anyone without impeccable firearms manners). I'm a big fan of the 870 for static home defense. I'm a big fan of the AR platform for longer distances and more active neighborhood defense. If I weren't such a lousy boater, I'd own all of the above, and a .22LR pistol and rifle too.