I know of a guy who supposedly knew guns real well and one day while going to clean his 25 auto was interrupted by the phone. Lets just say he swears the gun was empty when he missed a main artery in his leg by a fraction of an inch. No, they are not very complex but-and don't ask why the idiot dropped the hammer while the gun was pointed at his leg-but a revolver is easier to clear and a double action is pretty hard to accidentally pull through.
One other thing about autos that people don't think about too much is the matching of the power of a load to the recoil spring of the gun. If you fire an auto without enough resistance to recoil provided by the shooting hand you've got a failure to feed guaranteed. My buddy and I once loaded up some 'cheapy' lead reloads for his 9mm. We had no problems at all with feeding until we let his wife take a turn, every other shot didn't cycle the gun fully. If you decide on the auto route I'd definitely practice different holds on the gun while firing. No, I'm not saying women are limp wristed, that's just a gun design thing that doesn't take into account that people are different.
I think basically the .38 special double action revolver is the wayto go, especially when your talking about a self defense gun