As an former s8 owner and now the iphone 8,the camera on the s8 is a bit better imo.
It has faster autofocus which i do miss alot.
But maybe the pics on the s8 looks better because of the sharper and bigger Screen?
Personal opinion really, but from every review I’ve seen, and my own opinion, the iPhone 8 has the better camera. The S8 screen does make it look better than it is, due to it having a highly saturated OLED screen.