I missed the earlier discussion, but I perfer the .45 over the . 40, when loaded with approximately the same grain bulllet weight the .45 hasa shade higher velocity in most factory loads. The 9mm with 115 grain hollow points is faster still. My main weapon is a .45 my backup is a 9mm. If that is not enough I then revert to a .38 spl with hollow points. Use what you are comfortable wearing, practice, practice, parctice. Move, shoot, move and hit where you aim. Bigger is not always better, but I want something that intimidate with the big hole oput front.
S&w M&P 45
Kel-Tec P_11
Colt Diamondback