Best OWB holster for my G19 that I found was also at the best price. Check out this Link Removed site. Super smooth and snug fit with excellent retention release button. Much more ergonomic and secure feeling than the Blackhawk Serpa (which I have also used) and at a fraction of the price. Also has unlimited cant positions versus only 3 with the Serpa so you can do cross-draw, vertical, horizontal, anything. I have bought holsters for other guns and magazine holsters (same unlimited cant) from this site as well. Fast delivery and unbeatable prices. BTW I have no affiliation with the site, just like their stuff and the prices.
For a firearm like the Glock 19 with no external safeties, I like having it in a retention holster when OWB.
Enjoy.