I still have a bunch of .40 pistols deployed for defensive use. I bought my first Glock 23 when I turned 21 in 1997, at the time 9mm was for the weak/feeble and most LE was using .40. In the last 10 years I transitioned most of my practice guns to 9mm due to ammo costs, resale ability, and the commonality of mags/ammo to my 9mm AR. I haven’t sold off any .40 models yet, and I have two I’d never get rid of as they were my first and another was a gift from my dad. I keep a G23 in each car, one in the couch, one under my pillow, etc., but I don’t think I’ve shot one in a couple years.
On the Glock model 45/19X: these are my perfect Glocks. I have big hands and these fit perfect, while the ambi controls are easier for me as a lefty. I have 2 model 45’s, 2 19X, a G34 Gen 5, and a G17 Gen 5. I could be completely satisfied with all of my pistols being only the 45/19X.