I'd say avoid polymer frames like the Glock. I had a 9mm and the recoil on it was terrible, hurt my hand after a while. Then I got a .22, and the recoil was better, but I didn't think it'd be very effective for self-defense.
I finally went out and got a Ruger SP101 revolver, it shoots 38 special and .380 magnum. I think its the best of both worlds. The calibur is similar to a 9mm, you can choose between shooting at the range (38) or self defense (magnum), and the gun is all metal, so even though its heavier, there's less recoil and more accuracy.
Best advise I saw on here was go to the range and try as many guns as you can before you buy. It took me buying 4 guns before I found one that was right for me and my tiny Donald Trump hands.