the story with lillie is better in sun/moon tbh if you care about that

ultra sun has more things to do then sun

I'd say the story is better on the originals, the overall feel of the environment and ui looks a lot nicer, its more nostalgic and story focused. But if you want content (and more pokemon) go for the ultra ones. But honestly they are both amazing, su/mo is just more laid back.

There both very similar to be honest, just go play ultra it has more