First I would suggest that you go to a local range that has a variety of handguns to rent and try out a selection to see what fits best. This is my standard answer to this question. There is no one size fits all standard. To me the 1911A1 drops in my hand and points at the target without my thinking about it. You may not find that is the case, though I doubt it.
Second, you should pick a caliber that will STOP the attacker (9mm minimum). Do not get something that will depend on perfect shot placement to get the job done (.380 or smaller). The smaller the caliber the easier to control, the heavier the weapon the less felt recoil, the perfect fit is somewhere in the middle depending on the individual. I’m not anticipating being attacked by a grizzly bear in the suburbs of Richmond so .45ACP is plenty of stopping power.
Third, you should practice, practice, and practice some more. In order to be effective with any weapon you will need to rely on instant action, something that is only going to be available with practice. If I can’t stop the attack with the 15 rounds I usually carry then I should have brought a rifle.
Finally, you should put the best lawyer you can afford on a retainer basis if you are only going to disable the attacker. Sure thing the wounded gremlin will try to sue you for pain and suffering. Dead men only leave one witness to the event. When forced to defend my life, or the life of another, it is not a matter of disabling the attacker. I shoot until the threat is eliminated. That means dead. There are hundreds of examples of the attacker taking multiple hits with various calibers and pressing the attack. Dead people are no threat. If you do not think you can kill, then you probably should not carry to begin with.
all sounds very sensible. thanks.