I think who is making a game plays a great role so what I expect is some first party games to look better than most PC games at the time. It would be a combination of great developers providing an art style, better engine, more time to make the best looking game while most multiplatforms are not as good even if PC are much more technically better they wouldn't be using all that power to make the best looking game.
If you want the best visuals I would buy a PC for multiplatforms and PC exclusives and a PS4 for Playstation exclusives.
If you want the best visuals I would buy a PC for multiplatforms and PC exclusives and a PS4 for Playstation exclusives.