I agree fully with this statement. Just think the OP wanted to stir it up a little. With me it has always been location, location, location. I know that the FBI does hundreds upon hundreds of tests with different guns and different calibers and different....... Got nothing against them but, can tell you I will carry what I have trained with be it 45, 40, 357, 38, 380......... I know that some people think the sun rises and sets with them but, it doesn't.
Find a good gun in a caliber you can handle and train often! The fastest accurate shots is usually the winner. I have no illusions that 1 bullet of whatever caliber will stop the fight. You need to keep on fighting until the bad guy is not fighting anymore.