Don't overlook the effect of adrenaline. If you have never had to shoot at an enemy soldier or an attacking large animal, then all else is out the window, IMO. The reaction of shooting at something that is one or seconds away from killing you cannot be duplicated at a range. Short and sweet: if you are comparing between 10mm and .45ACP. I'd go with the gun that you are totally and instinctively comfortable with, that you can load, fire, rack, clear and disassemble in pitch black darkness. The gun you can use as easily as your toothbrush or car key is the one to go with, given that your range of caliber choices is as you describe.
Your world changes forever once your life truly is on the line, right then, right now. But it's somewhat like riding a bicycle. You don't know what that means until you've been there. Not trying to be macho or a preacher. I am overly wordy - choose the effective caliber you most enjoy shooting and are most comfortable with, especially on short notice. A high-powered miss is worth little-to-nothing.