I love to shoot my 9mm Browning High power. But My Colt 1911 is great too. I have never shot anyone so I am no real help. But if you hit the OFF BUTTON (the middle of the forehead) with a 9mm or even a .380, you will have no problems!
I know some cops who say that nothing beats the .357 mag from a 4 inch barreled revolver for sheer stopping power. It is still the cartridge that all other cartridges are compared to as far as stopping power goes.