The .40 is a great caliber - at least for me and in my opinion... Many will certainly disagree...

I find that I can squeeze off more rounds more quickly and accurately with the .40 vs the .45.

I have average-sized hands. A .40 in a double stack mag is a more managable grip in my hands and gives a greater rounds per magazine than a comparable single stack mag in .45.

The lesser recoil is helpful in multiple shots. I find with a .45 I tend to "milk" the grip after about 6-8 rounds or so... I don't find myself "milking" the .40 until about round 10-12.

I know: shouldn't be "milking" any pistol at all, but...

As compared to a 9mm, I like the added "bang" that the .40 provides.