Every hunter knows perfectly well that one tunes one's bullet and charge to fit the game one is after. The self defense community sometimes seems to forget this in reaching for numbers that do not always translate to superior performance. I like the .45 because it's optimized for the human body - that sounds awful, but if it's him or me I want something tuned to him.
A lesser known but quite capable .45 handgun. The Mauser M2 is built by SIG and designed with concealed carry in mind.
The Hatcher Report on handgun stopping power, written after the Phillipine conflict at the turn of the last century, concluded that, for sub-sonic rounds, only caliber had any effect on stopping power, i.e., knocking down a man with only one shot. The Report was written after soldiers equipped with .38s kept having the crazy Phillipine rebels keep fighting. That led to the creation and issuance of the 1911 .45. I haven't seen anything since that suggests any different. Incidentally, the Report also found that hollow points made no difference, again with a sub-sonic round. Jeff Cooper took all this info to heart, and recommends wad-cutters for the accuracy and ease of handling. Military ball ammo, I understand, made the 1911 more difficult to shoot than it needed to be. When the Army studied the gun and then started issuing Baretta 9 mms., it should instead have changed the 1911 load and bullet.