Re: 40 caliber, like or don't like
A .40 is a little snappy to be a particularly fun range gun for me, and range shooting is a little over 99% of my shooting. I mainly shoot 9mm, mostly because it's cheap and has become a world standard.
.45 ACP is fun to shoot in a different way, with its relatively low pressure and big, heavy bullets, but endless tests suggest you don't really buy much in the way of self defense over modern 9mm ammo or other .35+ calibers. Range .45ACP is almost twice as expensive as 9mm, so this choice is easy for me.
The only handgun I have a concealed carry holster for is a Sig 238 (380 ACP), but if I had to carry for work I'd probably be most comfortable with a 9mm, .40, .357 Sig, or other equivalent.