For IWB holsters I have two and both work very well. My main carry holster is the Incog holster by G-Code. It is a kydex holster made specifically for my glock 19. I wear it at the 4 o clock position but can be worn at several different positions including appendix carry.
The second holster I use is the remora no clip holster. I use this holster only when I cannot wear a belt like basketball shorts and sweats. It works great as well.