I myself have the Xbox One S and actually use it only as a 4K Blu-ray player.
I played on her earlier, but now she's just too weak to play most of the games at 1080p and often drops below 30fps.
If you have the money you get the X. Since you always have 1080p or more and 60fps in most cases.
The targeted frame rate is mostly identical for both, only the constancy is better for the X. So most of the 30 FPS titles also run on the X with that number.
That's a gigantic difference. The S is no longer a pleasure. I recommend you to buy in the offer, for example. Last at Saturn for 388 euro.
I have an Xbox one S and it works fine.
Although I have no comparison, but I'm satisfied with the price / performance ratio.
As an example Monster Hunter World. I have on both consoles and on PC. Only on the Xbox One S the game 864p often runs under 30fps. Not only does it look mushy, it also jerks and feels spongy.
The PS4 can hold the 30fps constant at least at 1080p and looks also sharp.
Only on the PC, the game runs with me in 1440p with 60fps.
or Forza Horizon 3. This does not run smoothly and does not look too pretty if you also play the PC version.
BF5 the same.
So rather take the Xbox One X and have a stable frame rate and a higher resolution.
Usually I get comments only when people contradict me.
Yes, the S has really fallen below the limit of acceptability in recent years.
Was then for me the better alternative to a 4K Blu-ray player what the price was concerned.