Interesting question. For me, living near the Rockies and being a hunter, I have a somewhat different list:
High Powered and scoped rifle: .270, .30-06, 7mm Mag are all ideal with ammo readily available
12 Gauge shotgun: Ducks, geese, home invaders (given a shorter barrel)
High Powered Revolver: .357 Magnum, .41 Magnum, or my favorite, a .44 Magnum for hikes, fishing trips, etc.: Availability of ammo and general killing ability on all "48 states" game including mountain lions and bears (though a .357 might be light on a large bear).
Carry gun: 9mm, .45ACP, .40, .380, 38 Special... Whatever fits your character.
I consider a .22 rifle or pistol nice to have, but I'd have those others first.
Just my opinion. Your opinion will undoubtedly vary for your particular needs...
Happy shooting!
WingRider