1: Reliable pump--always just works. I'd say Rem870 or Moss500/590 are the best "standards" out there.
2: Bullpup for tighter situations. Not a lot of options here, but the KSG is probably top of the list or a converted 870.
3: Semi-auto for your faster needs. I like the Benelli M1, probably others out there as I'm more into pumps for reliability.
That being said, I'm personally more a rifle and pistol guy, so for me, a bullpup self-defense shotgun is about the only one I personally would have any use for.