Either a shotgun is semiauto, in which case it's as unreliable as a rifle or worse, or it's breech loading and you get 2 shots which is not good for our adrenaline-filled, just-woke-up defender. I personally think revolvers are more finicky than ordinary semiauto pistols and I don't like the heavy trigger pulls (there's a reason why they're no longer issued as duty weapons), but there's room to differ there. More importantly, your ordinary skeet shooting shotgun or S&W 19 does not have a rail for a weapon light. Planning to use a gun in the dark without a flashlight is awful. Gotta know your target.

In general good advice starts with "use what you got", but I think the well-intentioned fudds telling people to use a shotgun or revolver are giving bad advice. If you're buying something for home defense you should buy a normal semi-auto rifle with a weapon light.