+1 to practice all of the above, commit to none of the above (to paraphrase pax a tiny bit). Realistically, none of us know how an intruder is coming in, what they want, or what it'll take to end the threat; so you need to practice for every possible contingency, and put your mind in a place where you can adapt on the fly and adjust to the scenario. Playing out your training drill without your head on a swivel is a pretty sure way to get killed. One of the smarter Corporals I ever knew referred to it as "Semper Gumby".
FWIW (and to answer the original question) I use a 2C maglight and a 4" .357 if I determine that a handgun is in order: so I can choose whether or not to employ the light without having to use my gun hand, and so I can hold it away from my body (even a blinded person can hit a bright light some of the time).
Due to my limited combat experience however, I definitively prefer a long gun (in this case a Mossberg 500) as I would almost certainly be tired, possibly intoxicated, and can use any "gimmes" I can get. I know that buckshot is far from "spray and pray" lethal, but having a weapon in my shoulder makes me a lot more comfortable when instinctively point shooting. Oh yeah, also because I live in an apartment and kinda like a couple of my neighbors
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