LCD screen protectors are a personal choice. Many people prefer to go "bare" but I don't want to damage a screen with a belt buckle, jean riot, or any of the many things that can damage it and remind me of my decision overtime I review an image.
As soon as I received my D500, I did a search on which screen to use. There are a number on the market ranging from $10-$20. I found a post and was pointed to one particular brand. "Works great and no bubbles" was the consensus, so I went with it.
I followed the directions exactly, and this was the result. They said you could remove it carefully and reapply if necessary. "Necessary" was four or five times, and still not a satisfactory result. I decided to live with it, and didn't want to spend anymore time on it. Overtime I reviewed an image or showed one to somebody, I felt a little cringe.
When I bought my D750, I definitely wasn't going to buy the same product. I went onto Amazon, spent way too much time reading reviews, and made a choice to try GLASS by Expert Shield. The application was simpler. Position on the screen, lock on one side with a piece of tape to get the alignment, then peel off the backing and done. It was that easy and it was perfect.
After a couple of weeks, I got fed up with the screen protector on my D500. Showing images to people was embarrassing. It's kind of like when you see cars with black out windows that are peeling - it does't look good. I went back to Amazon and bought another GLASS by Expert Shield for the other body. It felt good to peel off the bubbled screen and toss it in the trash. It went on as easy as on the D750 and I'm done.
I put one on my Sony RX100 III, which I keep in my purse and takes a beating. The screen looks great. They're $19.95, but it's going to be on your camera for as long as you have it. It works well and is easy to apply and has no detrimental effect on the D500's touchscreen. If you're going for a screen protector, this one does what you want and is easy to apply.