This goes to my original point, that in the majority of cases your emphasis is not on incapacitation or killing, but to make the individual stop. Hopefully to then run away.
Typically, I am very distance conscious. Within 25 feet (civilian Tueller Drill distance) I will have a large knife in the other hand. In a charge, I would prefer to be able to put several .22LR rounds through the individual than I would a single, larger caliber round, because I don’t trust my accuracy to be able to nail the rather narrow one-shot drop zone.
Far too often, as well, if they have a gun, it will be a large caliber, poorly aimed, with hits based on luck, so I will also concentrate on cover.
There really isn’t a perfect answer, because everything is situational, but in most cases, .22LR will fit the bill.
If I am in a situation where I have decided to use deadly force, I want to be sure the threat stops.
I don't want to depend on pain tolerance or drug free judgement.
I would prefer to be able to put several .22LR rounds through the individual than I would a single, larger caliber round,
I would prefer at that point to put several larger rounds through the individual. Why isn't that one of your choices? The options are not limited between too small to be effective and too larger to control. I think it would take a rather weak individual who did not train to be unable to bring a 9mm back on target. My pre-teen girls can.
but in most cases, .22LR will fit the bill.
But fewer cases than rounds normal proscribed for personal protection. It seems a bad choice form most individuals.