One Gun
For home defense....my Mossberg 500 Tactical with copper jacketed sabot slugs or good 00 buck shot......for out and about "on the town", my dearly beloved Sig P220 with Tritium Night Sights.....
Shotguns are just SO versatile. Often times when I get out of my cruiser I have the choice of my AR-15, my Shotgun, or just my sidearm. My logic? Shotgun every time. Why? Because I'm still going to retain my sidearm as a "backup", the shotgun can be loaded with just SO many different types of rounds (rubber ball, flash-bang, buck, bird, slug, etc.) I shoot a ton of injured deer/moose and the shotgun works EVERY time (very humane), can be good out past 150/200 yds. with the right ammo, can support a light/laser/combo, red dot or low magnification optics, etc., etc., etc. Don't get me wrong, I love ALL my guns for varied reasons.....but for the "all around" award, my shotgun wins every time!!!