I prefer to carry a S&W M&P 9c with an OWB holster, but I am not allowed to conceal carry at work. So at work I carry a S&W 637 38 Special in a Galco holster in the appendix position. I have carried at work for several months using this system and nobody is the wiser. I have an office job, but I am in and out of the warehouse all day so I am allowed to wear t-shirts, and I have no problems concealing my weapon.
My current appendix holster is a Galco Triton. It works but it's not perfect for me. I seriously thinking about G-Code Incognito Appendix system.
Garrett Industries Silent Thunder Slim. I have three for aiwb.
Silent thunder holsters are pretty amazing. I have the regular silent thunder which I wear appendix, or 9 o clock, or 8 o clock (left hand) and works great. Since it has adjustable cant and height it's super versatile and very easy to find that sweet spot. Highly recommend, won't be disappointed.
I currently am running a Blade-Tech nano and it works well for a mid-range holster. It's stable and has good adjustable retention. I am also looking for an upgrade though. So in the meantime I'll continue to carry with the nano. I'm carrying a glock 23 btw.