If I could only have one gun it would probably be a .22 model 17 S&W revolver. A Ruger single six would be nice too, as would any of around a dozen good .22 auto plinker/targe types.
You'd better find you a range in your area, go down there and talk to the people. Tell them your wishes, rent and try some different guns and get some instruction from the pros there. Then make your own decision.
I don't know about havingonlyone gun, but if I had to do it all over again (I'd do it all over you ... no, wait ...) I'd START my handgun training with a .22 revolver. Then when I had decent habits I'd get a gun for, like, y'know, business. But a good firearm with the lowest possible recoil is, IMHO, the way to learn to shoot.
I certainly agree with some kind of .22 plinker for starts...
Ruger of course, maybe 10/22, Mark III or one of the revolvers, depending on your preference. Doesn't much matter.
But if I could really only have ONE gun... ever...
I'd have to go with a 16 ga Mossberg 500 pump
There are some things that a .22 won't do... and they're important things.
"If I could only have one gun it would probably be a .22 model 17 S&W revolver. "
Good luck finding one!
I have one that I bought over 40 years ago when in High School....6" barrel; interchangeable cylinders for LR and magnum. My buddy had the "Buntline" model with what looked like a 12-incher - beautiful but too damn heavy.