Well putting aside that it is a slightly silly question, I like the .45 just because, since it makes a slightly larger hole (even without any expansion), it has a slightly higher chance of hitting a major organ, blood vessel, CNS, or supportive bone structure that a smaller round just might miss or only graze (again, this is only in very close call situations, so we're talking about tiny advantages here), which just might cause the BG to shut down, or fall down, more quickly, if he's trying to kill me - and yes I'm shooting to stop the attack, not kill, as a civilian - that much is correct. I used to think 10mm was the shiz for carry, but it actually has less diameter, and potentially too much penetration. If I thought that a good .45 round would not penetrate far enough in 99% of circumstances, then I would go back to the 10mm, but that is not the case - I think the .45acp WILL penetrate far enough in 99% of the defensive scenarios. I can see carrying 10mm for a LEO duty weapon, since it would be much more likely that an LEO would have to say, shoot through a windshield to stop a BG than me as a civilian would - not saying this could never happen to a civilian, just that it's MORE LIKELY that an LEO would need this extra penetration in certain scenarios, for two reasons:
1. LEOs are flat-out more likely to need to use their guns on an absolute scale, and therefore the number of times where a real penetration scenario might come up are much higher, EVEN IF the percentage/proportion of extra penetration vs. regular penetration scenarios remain constant as between LEOs and civilians.
2. Civilians only have a legal right to protect their own lives and that of their loves ones, in most states, not the average "other citizen", whereas LEOs do have that right (and arguably duty as well - moral and departmental if not legal). So, for example, if some idjit is about to drive their car through a crowd of people, producing a scenario of imminent death or serious bodily injury to many in that crowd, Joe Q. Public should just jump out of the way of the car, not shoot the criminal driver (unless his loved one is in the crowd, but set that aside). LEOs, OTOH, have a right to shoot this idiot even though he doesn't have a loved one in the crowd, since his job is to protect the general public.
Thus, I would personally choose 10mm if I were an LEO as a duty gun, but use .45acp for carry if I know there's going to be a high likelihood of trouble.