You guys may find this hard to believe, but prior to my doctoring days I was a gunsmith. No kidding. While I was a practicing gun doctor I never saw or heard of a broken Remington 870. Unbeleivably reliable, very strong and will last for generations. I’ve been out of the game for a bit, but I think the Mossberg has an aluminum receiver, which is not as strong, and possibly prone to missfires. Another plus for the Remmie is the slide has dual action bars, so a stuck shell is virtually impossible unless you pull the rim off.
As for home defense, no question a shotgun is your best bet. I’m a double man myself, with a Ruger Red Label and an SKF over/under, but you can’t beat the itimidation factor of shucking a shell with a pump.