In the early 90s, I want's a "duty" style pistol and I got a GLOCK 19. The reason I got a GLOCK 19, and not a GLOCK 17 is because I lived in NJ at the time and the mag cap was 15 rounds. GLOCK made a "Jersey Plugged" magazine at the time for the G17, but they were very hard to come by. NOTE: This was before the Federal AWB and therefore there were not 10 round magazines at the time.
Unfortunately, the G19 didn't fit me at all and it turned me off to GLOCKs for many years. Year later, when escaping from NJ and CCW was a reality, I bought a G27. At that time, there was nothing else in that class, 10 rounds of .40 in such a small package. I started appreciating GLOCKs again. I would eventually wind up with another GLOCK 19... only to sell it shortly thereafter, for the same reasons.
Note: I really like the full size guns. Had there not been the mag ban in place, I would have bought the G17 and things would have been much different.