I have the S8 and I tried the Otterbox Alpha Glass screen protector from Xcite. It's shit. Ok I'm being a bit harsh, it's good but you can ONLY use it with an Otterbox cover otherwise the cover will push the protector right off the phone and it will be completely worthless.
A bit of research led me to "liquid glass" screen protectors. You basically wipe some magic nano-liquid on your phone and leave it on for a couple of days without using the phone. According to the YouTube reviews you can then take a hammer to the phone screen without any worries.
For covers I tried the official Samsung Clear View cover which I didn't like that much because I hate wallet type covers. I'm now using the Spigen Ultra Thin cover from Xcite and I'm ok with it.