Honestly been using a regular screen protector. Been using this LK's Screen Protector. I used a glass screen protector on my Razer 2 previously but the curved display on our phone makes it a hassle. I thought I'll be all nitpicky with the feel of a regular screen protector but it's actually smooth and not all plastic feeling. It's not that expensive to try to experiment at least?
I was worried about the fingerprint scanner working, so I currently have this on my N20U. Works great! Usually I HATE any screen protectors that aren't tempered glass. But this one went on very easy. No bubbles, and it looks good! Even works with my defender pro case. Eventually I will go glass, but this works well.