I got my first pistol in .45ACP because I didn't know better. It is a great caliber and all is fine, except that I gotta bend and pick the brass whenever I shoot and loading it is more expensive.
All depends, I guess how much someone shoots.
If it is only 1000-2000 a year, caliber doesn't mather, however more then 5000 I will go with .40 S&W.
Few priced to compare:
.45ACP
brass - 100 bucks for 1000 cases one time fired
bullets - 120 bucks and up for jacketed (200gr)
.40 S&W
brass - most of the guys get it free, however buing is not expensive, around 30-40 bucks/1000
bullets - 90 bucks/1000
Loading about same
So, 1000 rounds for .45ACP will cost you about 80 bucks more then .40 S&W,
when you shoot in ,000's just imagine the savings???