I gotta add some things/rant.
I get annoyed by one shot stop numbers. How many of those people were about to run anyway? How many simply stopped so they didn't get shot more? How many were actually going to continue the attack until dead? Even a hundred or so examples for a given round don't really stack up to mean all that much.
Another good question is how many here have seen deer get shot with multiple 12 gauge rounds with vastly more power than any service size handgun, then go on to run 50-300 yards before expiring? Power is important, and accuracy is even more important, but in a gun fight both can easily mean next to nothing without a high volume of fire at a very fast rate.
In calculating combat effectiveness of any given handgun and round you have to factor in first the shooters needs for grip size and maximum recoil and muzzle flip as well as the best trigger configuration, followed by bullet weight, penetration for different clothing and building situations, bullet velocity, and hydrostatic shock value of a the bullet at the speed it will attain which has a whole lot to do with how well the hollow point will hold together and expand.
The fact of the matter is that learning the science behind all of these factors to someone uninitiated could easily take 20 hours of hands on work in a hypothetical optimum classroom setting, and way, way longer if you search out all the information for yourself like most people do. It's complicated to say the least, and very dependent shooter to shooter.
The other fact of the matter is that with maximum power HP loads in 9mm, .40 short and weak and 45 ACP, you get similar performance. 9mm is hot and peppy for its diminutive size, .40 is lower pressure than its parent round 10mm, and .45 is a low pressure relic which gets its power solely from width and weight. One or the other can offer various, slight benefits and offer differing statistics, but they're all about the same in terms of damage that they can cause. The differences in practical terms end up being about the grip size, recoil and capacity. It is because of this that so many people choose 9mm or .40 instead of .45. .45 only really shines as a military round when FMJ use is required.
I didn't used to think this way, and in fact I'm embarassed to say I bought into the .45 ACP hype for a long time. But I've come to realize that for small guns, 9mm is about optimum for power to weight, and that to step it up significantly from there requires .10mm, .45 Super or even .460 Rowland, which is a move I strongly endorse for those who can handle a firearm of that size and recoil.