Any headset claiming that images are improved by supersampling etc are using an old placebo effect using anisitropic and edge smoothing terchniques. It's a gimmick. It
might make a small difference to the overall image, but the sharpness can be done within any software video editing suite. It won't affect the Vive or Oculus as much as their smaller counterparts.
You won't get better than the Oculus and Vive pro at the moment, but the Go has slightly better resolution. Wouldn't personally waste money on it just for media though, the GO will NOT be getting the games you can play on the Rift, just a handful of the less demanding titles. Keep your eyes on Rift news later this year. You could splash out on an 8K headset if you have money to burn, but it's a long way off before mainstream goes to that resolution !
You can edit the 5ks to make them smaller in size and play more smoothly, but really, why bother when the 4K works and looks 95% as good ? No idea why 5K was ever thought up anyway, as it's ony usually used to showcase hardware rather an industry benchmark. The next feasible is 6K. Not going into it, if you want geek/tech talk, look it up