The best defense firearm is a 9mm, preferably Glock. Low penetration past target, high capacity, fantastic maneuverability in tight space (like your house or vehicle), cheap to train. all these other guns are shit for interior ops. Think about your hearing, if you discharge in a confined space the pistol is far superior (your still going to get rung but less stomach churn). Good in court, etc. Having an AR is good but in reality the best defense is what you can get to in a rapid response. Glock all day, AR is the second grab as I call it. You can deploy a pistol faster than the AR then grab the rifle while having one hand on threat. Train train train. Know your situation and backdrop, that AR while blow through all the walls. 9mm not so much. AR is a mid range think driveway threat, shotguns are dumb you and the kids will be deaf and stunned, unable to control threat situation.