I decided to make a second post for belt holsters. To make a long story story short, I will skip most of what I have tried over the years, and simply say what I like now, for the Glock G19. Outside the belt, I like Kramer holsters, made of horsehide. The Vertical Scabbard is a winner. I have these for pistols other than Glocks, that I have carried in the past, too. With my retirement from LEO-ing imminent, it will soon be time to transition to being a lefty, as age/wear/tear have not been kind to my right hand. (Fortunately, I am a natural lefty, with such fine-motor-skills tasks as writing, and developed ambidextrous shooting skills since day one.) I recently bought a lefty Kramer Vertical Scabbard, horsehide, to be my "primary" carry rig, in retirement.
If Kydex, or a similar thermal-molded plastic, is your preferred material for outside-the-belt carry, JM Custom Kydex and Raven Concealment Systems make excellent products, that I have used regularly, for carrying Glocks.
For inside-the-trousers rigs, I am finding JM Custom Kydex to be second to none. The JMCK site has good advice about which holsters to select for specific carry positions and body types. They are responsive to e-mails, too. Good thermal-molded rigs are available from Dark Star Gear, Concealed Carry Concepts, and Dale Fricke, too.