I'm no expert or master shooter, but I am somewhat discerning about how guns shoot and feel.
I've had XD, Walther, M&P, Glock and Sig models to compare over the last couple of years.
Without a doubt, I'd put the Glock down as the most reliable, most aftermarket parts, and as the worst to shoot. It's just crude. The others are all so much better, OUT OF THE BOX, than a Glock. Everything can be "fixed" but it shouldn't have to be.
You can't go wrong buying a Glock, but you certainly can buy a lot better.
Specifics:
The bottom of my trigger finger gets rubbed raw when shooting a Glock. Yes, I can (and will) take some abrasive to the inside of the trigger guard and smooth it out, hoping that will help.
The trigger safety hook gets hung up sometimes. I've been told that I must be holding it wrong. Thing is, when SHTF who has time to figure that out. Put finger, any part of finger, at any angle on the trigger and pull it should fire. Don't have that problem with any other guns.
Trigger pull is just rough comparatively.
The magazine witness holes are hard to discern. On that topic, S&W has the easiest to see, but they're odd on one side and even on the other. For competition that's okay, but for real-life tactical not so much. The Sig has easy to read holes on both sides, but only at 5, 12 and 17. Not great for competition but all you need to know if you're checking in a firefight.