9 mm or .38 would be what I would look for. Ammo can be had for either fairly cheap and niether has that much recoil compared to other defense rounds as long as you stay away from +P loads.

There are others, but the stopping power will not be that great.

I would suggest a revolver in .357. You can shoot .38's to practice and then load it with the .357 mags for defense. I would practice with some of the 357's just to get familiar with them though. And for a first time gun owner a revolver is simpler, safer and a little cheaper to use and own.

A .380 auto would work as well, but it's pretty much like a 9mm short. Might as well just get the 9mm instead.

I highly suggest taking a gun safety class geared towards pistols and defense if that is what you are looking for.

Paul