I carry 9mm and love shooting it but I find myself running low on .45 more often cause my 1911's are my favorite semiauto in my collection to shoot . I should try a 1911 in 9mm one day to know for sure which I prefer.
I have a 9mm on my nightstand (G17), two M&P's in my carry rotation (9mm and .40S&W), and target pistols in .45ACP. I like them all, and might someday have a .45 as my HD pistol.
I also have pistols in 22LR, .38 Spl, .357 Mag, .41 Mag, .44 Mag, .45LC, .454 Casull...crap I might have forgot something.
The big ones that I am missing are .357 Sig and 10mm. Guess I'll have to scratch that itch sometime.