For no good reason I can think of, all my concealed carry holsters are leather- what few I have.
I use the above mentioned inside the pants type for my Bulldog, and a simple leather belt slide for my 1911. I've had the belt slide for so long I can't remember who made it. The very few times I carry a Browning P35 instead of the 1911, I use the same belt slide.
So far, those 2 holsters have been all I use for concealed carry. Obviously, I need a few more handguns, so I can explore the leather/nylon holster issue.