My "what the hell was that" tool is a boring old Glock 23, with a Streamlight TLR-2 light / laser combo. That gives me a way to see, a red dot to make the bad guy think twice, and 13+13+1 rounds of Federal HST 180gr .40 cal to convince him that leaving quickly would be the best plan of action. The short barrel shotguns are cool, but honestly I've never felt wanting in a "first strike" weapon. YMMV, etc.....
Worth pointing out that the cool thing about the Glock 23 is that with a conversion barrel and some magazines, I can shoot 9mm or .40 from the same platform.