40 has a very characteristic "snappy" recoil. It's not as easily manageable in a firearm of similar size (and nearly identical specs) as a 45 ACP. I can send lead more accurately downrange with just about any 45 compared to a 40, the edge narrows as the guns shrink.
I prefer the 357 SIG, and converted my 40s over to it--I'd shoot it more, but it's expensive... The same goes for 10mm, it's a great alternative to 45, but it's expensive and any gun you want to shoot that round accurately with is a hand cannon.
...so don't like the recoil of 40 and I'm more accurate with 45. SIG is too pricey... 10mm isn't that practical... that brings me back to 45.
There's a reason the 45 round has survived over 100 years. Any gun can be shot accurately. To some, like me, it's easiest to shoot a 45.