This Dendrobates Galaxy S8 Screen Protector provides great scratch protection while still being very slim. Once applied, it becomes hard to even see that it's there. The protector leaves the screen very smooth and easy to swipe unlike some other options I've tried which add some rubbery grip, which is bad when it comes to swiping.
Depending on the case you use, this protector may or may not get peeled up on the edges, however, I found that if this happens with one screen protector, it will happen with them all. The case is the deciding factor. So if you're having trouble with screen protectors, try a different case.