i personally believe with the right ammo any of the choices are an effective carry cartridge. I chose the 40s&w becasue of the ballistics and energy, but recoil is still tollerable. I would have chosen the .45 but the recoil factor limits the speed of accurate follow up shots. the 9mm is a great round because of cheap target ammo, (when able to be found) and good defense ammo.
Choose what you like but I will keep my Glock 23 in 40 s&w