I like the 10mm or the .41 Magnum. Either has it all over the .45 ACP, the .40 and the 9mm, except for over penetration. All the way out to 200 yards both have as much, or more knockdown power than the .45 does at 25 yards. I carried the .45 ACP Remington Rand, and it never failed me. I like the .45 ACP and the .40, but they are not as powerful as the 10mm or the .41 Magnum, and I always felt I should never send a boy to do a mans' job.
Yes, I do have 2 .45 ACP's, 3 .45 Colt's (Long Colt to the uninitiated), a .40, and 2 9mm's. The ones I favor, are the 10mm and the .41 Magnum, and neither is the handfull that everybody claims. I can fire either one with either hand, or both at the same time one in each hand. Yes, I like my .44 Magnums too, but they are not the subject of this discussion any more that the 10mm and the .41 Magnum.
Since you are debating the .40 vs the .45, the .40 is supposed to be a little better, but you need to shoot it to figure it out for yourself. What is one mans' junk is another mans' treasure. All of these people shooting .45 ACP's, for fun or Competition, didn't happen by accident!