So which is it? Is it that the .45 edges out (i.e. has a slight advantage over) all others, or is the advantage so great that concerns over capacity, etc. are effectively irrelevant in the fact of the superiority? You've argued both.
These discussions often take a defensive tone, which I am seeing now (not necessarily from anyone in particular). Let me be clear if I have not already:
Caliber selection is a wholly personal choice. My concerns are not likely yours, yours are not likely mine. I worry about 4 things when choosing a handgun and caliber for carry. Capacity, Caliber, Concealbility and Platform/Reliability (ordered from lowest concern to highest). Working backwards I research the most reliable manufacturers and models in my price range. I define a key list of features I must have (i.e. manual safety or decocker etc...) as well as some I would like to have (standard accessory rail, bobbed hammer or grip) and discard the rest. Then I pick out those which size would allow me to conceal the firearm well given most circumstances. Using those criteria I narrow it down to the 4-5 models I would consider, then I look at caliber. With most firearms, they are avialable in at least 2 of the big 4 (9mm, .40, .357sig, .45). I then make comparisons based on capacity (i.e, if it is available in a .45, does it have mag capacity of at least 8 rounds. If it is a 9mm, are hi-caps readly available and inexpensive etc...). I then decide which of the platforms I would like to try and I either find someone who has one to test out, rent one at a range or, price permitting, simply buy it and test it out. Once I find the largest caliber handgun that has the minimum acceptable number of rounds for a specific caliber in the mag that feels nice, conceals easily and I can fire well, I then have my trial carry piece. I then test it for function with a few different ammo brands and types. Then it becomes my full-time peice. I put a lot fo thoght into it, and a lot of my decisions are subjective to my own input and thus biased. I couldn't choose a handgun for someone else to carry or pick a caliber for them, but I can often add some data to their search and some advice in certain areas.
What I was saying about the "slight" advantage is this:
On paper it may only be .10inches of expansion, .5 inches of penetration or a "slightly" larger wound channel, but you're betting your life on that + or - .10 inches of expansion, .5 inches of penetration or "slightly" larger wound channel. Nascar racecars are very similar with "slight" differences, yet we always have a winner, not likely to tie there. The win may only be by a thousandth of a second, but it's a win. When my life is on the line, I want that .10 inches or .5 inches or "slight" edge. Some may feel comfortable without it, gaining increased attempts to incapacitate. And that's cool. As I said earlier in this thread, under stress, often your groups will balloon into monstrous balls of inaccuracy. If that is a concern for the user, then they would be best served and likely more comfortable with the increased capacity that something other than a .45 can give you (other than the rare exceptions). Or if recoil is a concern, a smaller round might be in order as well. I would not laugh at anyone or have words over someone choosing 9mm as a carry or defense round. I have in the past, firends of mine do, people I respect do as well. I choose otherwise, my personal concern is not my group size under duress or controlling the recoil of a larger round, I have confidence in my own ability to perform under such situations. I also don't plan on repelling a terrorist invasion with my handgun so capacity,
for me is moot. And since capacity, in my case, is rendered moot, I
want that slight advantage on paper that the .45 gives when I can have it. Because that slight advantage, even if others fail to admit to or see it, does translate into an advantage on the street going bullet for bullet. The .45ACP is far from a magic bullet, but it suits my needs exactly, which is why I carry one. YMMV.
I'd tote my .480 Ruger if I thought I could find a left handed carry rig for it 
