I agree that a 12ga is best for HD, FD (Family Defense, is that a thing?). EVERYONE knows the sound of a shotgun racking and that alone may be enough deterrent. But I'm a pistol guy too so if you go that way, any quality model above 22 will help you sleep as long as you get comfortable shooting it accurately. I keep a P226 40 in the nightstand.
Shoot smart. Shoot S-Mart.