My question would be which handgun points best for you? Under bad lighting conditions which handgun can you hit the best with when you can't get a perfect sight picture and need to get a round off quickly with?

Next issue for me is capacity? If you get into a fight under bad lighting conditions between bad lighting and the stress of a fight your shooting is not going to be as accurate as it will be on a target range.

Finally I see the 9mm and the 45ACP as being close in effectiveness. Not equal but close assuming high quality JHP rounds. I'd pass on the 380 because we're looking at a house gun situation not deep concealed carry.

My answer is a full sized Sig 250. 9mm high capacity, night sights w a frame mounted light. Has a DA only trigger w 2nd strike capacity if I get a click rather than a bang and have my other hand busy. Trigger isn't as nice as a 1911 or a good revolver but feels kinda like the DA pull on a S&W revolver.Note I said kinda like not just like. This model also fits my hand well. Your hand isn't my hand and for you what fits me doesn't count.

As for tactics turning your lights out inside is good when you think the threat is outside. If I've got a bad guy outside I don't want to be lit up inside in case it is someone intent on doing harm. I want him lit up and me in the dark. I also want him to know that I know he is there. My preference is for him to go away as fast as he can run not get in a gunfight.