A lot will depend on where you live (city apartment, suburban house, out in the country), and how much training you think you can squeeze in on short notice (buying a gun without investing the time to become proficient with it, which at a minimum involves a full day under a competent instructor, is a BAD IDEA).
What do you think of the Mossberg 930 SPX vs the Bennelli M4? I like the fact that the Mossberg is half the cost of the Bennelli.