At this point, I'd be more concerned about being on the right side of the law when using lethal force than the particular specific type of lethal force I have at hand.
Drawing on my military experience I think it's prudent for me to stick with an AR, simply because operating it is muscle memory at this point. I can keep that much more of my situational awareness on the situation at hand instead of wasting 'operator headspace' on manipulating a weapon system I've spent less time using. But I'd feel pretty comfortable with a 7 or 8 round Benelli or 870 full of Brenneke slugs or Flite-Control if that's what I happen to have. A 1301 or Benelli has been on the 'short list' for awhile but I missed the chance to grab one before all the current craziness started.
There's a 'why not both?' argument to be made, perhaps, for a vetted & tuned Saiga-12 or VEPR-12 with a drum magazine. But short of a belt-fed machine gun I can't imagine a worse weapon system to show to a jury.