I used to keep my converted (a la Tromix) Saiga 12 gauge with a folding stock and a 10rd magazine inserted by the bed. The reasons being the ease of use (it points more naturally for me than the Benelli it replaced) and the firepower. Reliability is likewise unquestioned. Also - because of the Kalashnikov gas system, I believe - it's the lightest-kicking 12 GA I've fired. So much so that I thought, in a pinch, the wife could put it to use with reasonable effect.
Then I bought my first revolver. That, coupled with the fact that we're having our first child in a few months, means that I've gotten in the habit of feeling perfectly safe with a 6" S&W 686, loaded and with a couple more speedloaders at the ready, in a small safe on the floor right next to the bed. It, likewise, points very naturally. There's certainly less power than the shotgun, but I don't feel undergunned when it's kept loaded with the nasty 158gr Federal JHP load. Reliability, again, is a non-issue.
The next project is to finally make the time to get the wife some more training with what will be her "house gun" when I'm away - the Beretta CX4 Storm carbine in 45 ACP. Hell, I like it enough so far that we may just adopt it as the primary house gun. I'm also thinking of hunting down a Cougar in 45ACP for CCW.
Anyway, that's what we've got and the thinking behind it. I'm certainly no expert. The only rule I go by is - if you noticed - what points (for me) the most naturally. I sleep like a bear, and am hell to get up - I tend to need a couple of minutes to be totally with it. I'm sure I'd be "with it" much quicker in a crisis situation - maybe not, though. Either way, I like having close at hand the tools that I'm most familiar/comfortable with. I'm much more confident that, in the mental fuzz of being rapidly awakened to deal with a home invasion, I'll be better off with these guns as opposed to one of the tacticooled-out ARs that sit in the safe.