Accuracy, Power, Speed.
You can be slower if you have the drop on the bad guy while hiding from hard cover.
You can win with a .22 if you use enough and hit where you want to.
There is no substitute for accuracy. Learn with the lower calibers and work your way up. Contact an IDPA club in your area to learn how to shoot under different circumstances.
Proper shot placement is always critical, and a wide variety of cartridge sizes are lethal when accurately delivered.
But there’s just that extra margin of oomph that I like about the .45 ACP over the others.