I voted 9x19 even though my current favorite carry gun is a .357. Also I have been known to carry a 380 from time to time and have yet to meet anyone brave enough to stand in front of it after they finish making fun of it.
.45 acp. I've owned and carried 9mm, .357 mag. and .38 special at one time or another over the years, but I keep coming back to 1911s in .45. The others are all adequate for the job, but those big, heavy hollow points make me feel most secure.
9mm for me although during the ammo shortage a couple of years ago I thought about switching to the 40 since it seemed to be about the only thing that anyone seemed to have in stock.
Used to edc a glock 26 w/ glaser blue tip rds until I sat down and compared a 9mm to 45acp. It's just so big!!! And we all know size does matter. I miss the high capacity, but love the stopping power.