The 1911, chambered in .45 ACP, has been going strong for 100 years.
Only 100 years? To me the only REAL .45 is the .45 Long Colt.
Anyway, as fun as these caliber wars are--and I always seem to be involved in one--truth be told, there's not a huge difference between 9mm, .40 S&W, and .45 ACP.
Some people naturally tend to gravitate toward the extremes regarding performance, namely higher magazine capacity versus greater wounding potential per round, and those people often believe that .40 S&W is pointless. Others tend toward compromise regarding endless, age-old controversies that will never be resolved, which is probably one major reason .40 S&W has been such a success (three is the perfect number--one to cover each extreme and one more to split the difference).
Whatever the true potential of each caliber is, one has to deal with whatever reality places before them, in addition to other practical factors (e.g. cost, recoil, effect on grip size, artificial 10-round limits imposed by law, etc.). It's better to choose the specific loads that will achieve the desired effects, regardless of caliber, and see what options that gives you in other areas according to caliber and the preferred handgun design (the practical factors mentioned above)--anything else is simply bias for one reason or another. Some biases are alright, like preferring larger rounds, but many others are just silly. Also keep in mind that each load in any caliber is a separate design, and some of the basic JHP designs, for example, may work better at some sizes and velocities than others.
The reasons I chose .40 S&W for my primary self-defense handgun are: living in California I can't have more than 10 rounds in a magazine anyway (I should move back to America while that's still legal!), negating that advantage of 9mm; .40 S&W's recoil does not noticeably affect my aim or followup shots; in loads where the expanded JHPs were of equal diameter, .40 S&W penetrated several inches deeper than 9mm, and in loads that got equal penetration, .40 S&W had a slightly larger diameter (not much difference, but these are still points in its favor, even over 9mm+P); there were handguns that fit the small hands of some members of my family and could still hold 10 rounds, which is an advantage over .45 ACP; I secretly wanted to (due to bias) but could not find a comparison that proved definitively that .45 ACP was ballistically superior (I could get a wider wound channel but would have to sacrifice penetration for it, and I favor penetration), so that was pretty much a wash; and finally .40 S&W is less expensive than .45 ACP (not a huge deal or else 9mm might have won out anyway).
I wouldn't fault anybody for choosing 9mm or .45 ACP--both venerable old calibers that have survived this long for good reasons--if either were a better fit for them, but .40 S&W fits right in between them and I'm one of those people who try to avoid extremes when given an effective option anyway. That said, at the end of the day, there is just not that much difference between these calibers.