In my opinion, the choice between leather and nylon boils down to personal preference – there are plenty of truly outstanding holsters made from each of those materials. Leather might be more comfortable, but Kydex is immune to moisture and sweat. Kydex is also lighter and thinner, so if you’re carrying inside the waistband, the overall width of gun and holster might be smaller and more manageable. Then again, Kydex against raw skin is not the most pleasant sensation. They don’t make boxer shorts out of Kydex for a reason. As you’ll see by the photos here, I use leather, Kydex, and a combination of the two, so it’s really a personal preference decision.