Pretty good thread going with lots of options. I'll add my two cents anyways.
My buddy has the Alien Gear 2.0 and loves it, though I don't know how much he actually carries. I have two that see regular rotation for my 23 gen 4. One is a kydex Overwatch Treadstone IWB holster, pretty slim and light. My favorite attribute is that I can easily clip it on and off and its reasonably effective and comfy. I did elongate the clip screw holes to allow for great cant, but IMHO it rides a little low to be comfy IWB unless you have very baggy jeans.
My other holster is the little old, el cheap Glock Sport Combat holster. This is an absolutely FANTASTIC holster and by far my favorite for carrying! I have worn it walking/running the dogs, around the house, working on projects and even on a 12 hour long road trip with pretty much perfect comfort. Great draw and presentation and strong retention. All this for under $15 shipped. One day I'd like to get a nice leather paddle holster but until then this does nicely. Even rides a little tighter with less "printing" than my IWB holsters. I'm not sure how long-term durability will look since the belt loops are pretty thin, but so far its held up great. If/when it needs replacing I will definitely add a new one to the collection; even if I have bigger and better.