This is like a Mac-vs-PC argument. So I ought to have the sense to stay out of it, but here goes.
Having ouwned three of the things, I now only have one: my ancient (7/89) Glock 19 that looked beaten to hell when I bought it and hasn't been improved through years of deliberate abuse and neglect (using slide as a hammer, dropping in dirt, tossing, etc.). The only parts failure has been a broken trigger spring. I wasn't fond of the 23, though I wish I had kept the 21, which I sold to buy one of "God's own" Colt Government models.
Some notes
Reliability: good, but not perfect. The 19 is not reliable with all ammo in the same predictable way that a Beretta 92 or Sig 226 is. Give it ammo it likes (ball or fairly rounded HPs) and it it feeds perfectly. Better than 1911s. Not as good as my P7.
Durability: Except for the trigger spring, no breakage. Not bad for a heavily used, 11 year old gun. From Glocks I've seen, the durability is unparalleled. They don't rust, and the parts don't break. The early, non-drop free magazines are kind of fragile, but that's been remedied with the new, FML mags. If you can't get the full 10 rounds into them, by the way, eat more Wheaties or drink more milk for God's sake. It's not like loading an SMG mag by hand.
Trigger: It can be learned. I find it easier to deal with than a crunchenticker, or about the same as a DA revolver. With the short reset, it's like a mushy single-action. Could be better, but could be a lot worse.
Overall, I like Glocks, though not without qualification. They're small, simple, light, durable, reliable, and adequately accurate. I don't care for Sigs, though in most respects they are better guns. 1911s, yech. Nice to shoot, but overly complex, not reliable out of the box, and overpriced.