One thing always stood out for me from Jim Cirillo's books about his days in the stake out squad.

He focused a lot on bullet contour and a wide and sharp meplate; writing that when a bullet struck the bone, especially the skull, at an angle other than 90 degrees, it would tend to deflect and ride the contour of the bone. Jim was a proponent of revolvers for their ability to have a wide/sharp WC or SWC, or single loading a wad cutter in the 1911 as the first round, followed by the widest profiles that would feed from the magazine after that first shot.

One thing that I think is nice about the 45 is that it offers the best chance of a wide nose vs the more sharply tapering profiles in 9mm.

Of course, I am writing this as a lover of the 45 GAP, but its close enough for me. =)