My normal home defense weapon is a 9mm Ruger. Yes, that is more than enough for a single attacker, but my home was broken into once by a drug junkee who had been part of a gang, so I don't mess around. I'm an old man who doesn't get around like I once did, and I have a family besides myself to defend.
My CCW weapon is a small semi-auto. I am licensed by the Sheriff to carry it, but normally it is in my car.
My serious situation weapon that I bought for worst case scenarios, but I use it mostly for fun at the gun range. If things get out of control like they did in the LA Riots or during Hurricane Katrina, or the tornadoes of 2011 in Alabama, it becomes my primary home defense weapon with my 9mm as backup. I don't expect an "end of the world" scenario, but I've been witness to society in disaster situations and if you've been through one, you probably have at least what I own. Some people (not me) have full auto machine guns, and they are for a combination of a collectors item, fun at the range, and worst case scenarios. If the worst case ever happened, I'd hope that just the site of my weapon would deter criminals, and if that didn't work, I'd shoot over their heads or with tracer rounds to attempt to defuse them or scare them off. Taking a life is ALWAYS a last resort, when you or your family is under direct and active threat, and all other attempts to deter attackers have failed.