Long before I started shooting 9mm, I shot .45 ACP. I suspect that is the case for most guys who were actively shooting in the early 90s, shooting USPSA.
I shot a 1911, and a Glock 21 heavily during that time period, plus my work guns were .45s.
Also, I was always a .44 mag fan on the revolver side. In fact the .44 magnum is the first revolver I bought for myself when I became old enough, and I have never been without one since then.
These days I shoot more considerably 9mm than 45, but still consider the .45 a favorite. The 9mm is just simply practical for my applications.
It is pretty hard to go wrong with a basic 9mm service auto, a 5" .44 Magnum, and a 1911 .45.
All that said, I also shoot a fair bit of .38 Special, since I always have a J Frame in my pocket.