Waaaayyy back in 2004, I attended my first ever defensive handgun course with Clint Smith at the old Thunder Ranch down in sunny Texas. Even though it was October, it was still 95F. About 50F hotter than the plains of Nebraska.
Anyway, I toted along my first centerfire handgun, a Sig 220ST. The beast. The anchor. Because I was new to this whole handgunning thing, my marksmanship sucked. I still managed to learn a lot though. Even more once I learned I needed to stay hydrated and set aside my ego.
Since then, I've managed to elevate my marksmanship all the way up to mediocre by USPSA standards. Hot rod by pasture tin can rolling standards.
Long story short, I noticed that in that class of 30 some students, about 80% of them were running Glocks. Even the civvie types.
Every subsequent training class I've taken since then, I've noticed the same phenomenon, Glocks. Lots of them. I've witnessed what I consider some phenomenal shooting with Glocks both in classes and in matches.
Somewhere in there I think there's a clue.
Take a class with a good instructor. Take another class with a good instructor. Practice what they train. Learn the Glock.