I have used glocks at work for the last 18 years. We have been issued the gen 4 glock 22's. I have not had a problem with mine but everytime I show up at the range they are changing out one part or another to fix problems they are having with a lot of the pistols.

I don't think thye are having problems with the 9mm or 45s but I don't keep up on that part of the industry.

A good gen 2 or an early Gen 3 and you should be good to go.

The new polymer Sigs I would stay away from. I have not heard good things especially with quality control.