For guns, I don't think brand matters as much as functional reliability. So some web research, or talk to gunsmiths and vendors about that. As for rounds, I think it depends on your situation. In a little house in the middle of a western ranch, you don't have to worry about the neighbor's kid sleeping on the other side of the wall or hall, so your situation will make a difference and you need to do some research on loads as well. What you anticipate defending against will also make a difference.
In my area there are a lot of home invasions, and homes are all packed close together. I'm also concerned about the fact that literally anybody can buy a swat uniform and body armor on the web, and shout 'Police' when they bust in your door. So I like frangible slugs (it'll knock down even a big guy in a vest) and #1 or #4 buck. Those will find plenty of opportunities to get past armor or hit a moving target. I also like a short barrel, open choke shotgun for 'home' work. And I prefer a pump because in a regular 'burglary' kind of event the sound of you working that slide should chase anyone out of there fast - so you don't have to shoot anyone or take a chance of being shot either - and if they don't run from that you know you need to shoot to 'stop them'. But, as I said, your circumstances may imply different choices.
And just BTW, I've never had to put the theory of my load choices into practice, so I can't swear they are the best options at all. And practice reloading your gun in a big hurry in the dark too. No fumbling and no dropping shells.