I have never used any leather gear because my department leans more toward tactical/practical rather than looking pretty. I've worn Safariland Nylok gear for a few years now. It is light weight, and looked good for the first two years, but now it's starting to look faded, and frayed. My guess it's do to all the rubbing against the back of the seat and center console, and the salt/sand from the winter. I have recently replace all the Nylok gear with Safariland STX Fine-Tac. So far so good. Looks like nylon at a distance, and dirt and "accidentally fired OC" just wipes right off. (which by the way sucks when your sitting in you car and you hear a faint hissing sound so you start looking for where it's coming from and you start coughing and you thigh feels like its on fire)
Another suggestion is the new Levitation Gear also by Safariland. My friend with the Lowell PD got it. It is by far the most comfortable and is so convenient. All the gear attaches to the outside of the belt so there is no need to remove your gear to add new items, and doesn't have any hard points around the hips. The gear looks cheap (that's the best way I can describe it), but that might just be the leather option. It might look good in nylon.
We tend to lean more towards "looking pretty" on my department. Everyone wearing the typical uniform here wears leather gear. We find it just as tactical and practical as nylon gear. Plus, it lasts at least as long and it shines well.
Sometimes "looking pretty" can make a difference when dealing with a righteous bad guy. Looks can be a determining factor when a suspect decides whether or not he is going to take you on. If you look like you know what you're doing and if you look like a squared away copper, the suspect may decide to go along with the program rather than fighting with you. I've seen it happen that way many times over the years.