Shot placement is far more important than caliber. I'd rather be shot at by a street punk with a 45 than somebody like Specops with a .22. Way back in the early 90's when i was a dealer ans shot a lot and stayed up on it there was some published material about 1 shot stops from hand gun, i'm sure teh info is still out there and updated, Maasad Ayoob and, shoot can't remember the other guys name did a lot of it. Off the top of my head I remember the #1 1 shot stopper was .357 125 gr jhp, 9 mm and 45 were about the same with the 45 200 grain CCI round and the Federal 115 +o 9mm load, 40 s&W was just starting to come out and looked like it was going to be a real good 1 shot stopper. Maybe if i get bored at work this weekend i'll see what i can find. In my time as a dealer and avid shooter I have noticed a lot of the older guy favor the 45, and a lot of the stories are just that, stories, I say that because they all sweared by 230 grain ball ammo, which is not a good stopper at all. By anyway, as i stated, placement is everything, actually tactics to avoid a gun fight is everything, shot placement comes next.
Yep, I've read a lot of Ayoob's stuff, and the 125-gr .357 Mag was famous for ending gunfights with a non-lethal hit.
I'm carrying 10mm Glocks loaded with Cor Bon 135-grain JHPs at about 1,400 fps. Pretty closely matches the .357 load above, and comes with semi-auto capacity. The .357 Sig will likely be my next carry caliber added to the rotation.
I actually corresponded with Ayoob on the 10mm load selection a few months ago.