Lucy is a PWA 20" light barrel AR15, with which I am accurate (with no wind) out to 1,000 yards.
Helga is my Saiga-12 AK-shotgun.
Heather is the two-tone (ODgreen+black) M4 that I built for my youngest daughter.
First gun always is my Remington 341 Sportmaster .22LR, Bolt Action, 24" Barrel, Manufacture Date 1933. Rigged with a two point nylon military sling & Q.D. swivels. Open Sights. I've had it for 50 years, and have no problem using it either right or left handed. And from a rest, left handed, it will put out an accurate rate of fire about twice what the Warren Commission says can be done with a bolt action rifle. It carries easy slung, and a thousand rounds in a SAW pouch is packable. It's what I'm best with.
I do like my Glock 21, but I'd have to go with my S&W 500 Magnum. Only because it will certainly put down anything out there, and with all the oddball genetic science we have now, finding a T-Rex on your front lawn is not totally beyond the ream of possibility. The 500 can dispatch it, and I can go back to my coffee & reading my newspaper.
I could never choose and hope I don't have to. Yes I am the first one to ruin it and not be able to choose.
I have so many guns that serve different purposes. I also have guns that were my fathers and could never part with them. Some of which are collectors. For instance, I have two very desirable Winchester Model 43 .22 hornet bolt action rifles. One of which, my dad bought before I was born and the other he found while in Tennessee once and bought it just because of what it was and that it matched our other one.
Too hard to choose here but I guess it would definitely be a hand gun and a shotgun since the shotgun is so versatile; you can defend yourself with it, hunt big game with it and bird hunt with it.