I'll put a vote in for the handgun, but only because I don't like the mossberg and using a long gun for home defense does have it's disadvantages.
I'd certainly use fragmenting ammo like others have said. If a stray bullet goes into your neighbor's house, it's your responsibility.
In a larger sense, IMO which path you go down should be your choice, not others... especially not on the internet. Research, and make sure you get something that suits you and anyone else that might need to reach for it (wife, etc). Above all, spend the time practicing at the range, and make sure everyone is comfortable about it's use, location, etc.