When I teaching Personnel protection school for the local range as a NRA instructor this question came up a lot. I always replied in this order 1: 870 shotgun 2: revolver 3: semi-auto Why? simple 1:shotgun is very easy to use, has large target area, difficult to miss intruder, training is minimal 2: Revolver is simple to use, but more training and discipline is required. When adrenaline is pumping you always fall back to your most basic training and instint. hence more training 3:Semi-auto most difficult to use and the most training is needed. I had one student actually tell me that a .44 mag was his choice! I merely replied How many walls do you want it to go through? You have kids? He said, yes. I replied to him think about it. After class he told me that maybe that was maybe a bit much. I said you think! Personel carry .357 is tough to beat. Ask around from some of your buddies at the range what they carry. For home I like my 870 rock reliable,easy to use and scary Good luck and be safe