The advantage to the silver iPhone X bands, it’s just ‘raw surgical stainless’, so any scuffs or light scratches will easily be able to removed with a polishing cloth from Cape Cod, [Which I highly recommend], the only concern with the gold bands, is if that scratches, you _cannot_ use a polishing cloth with PVD coatings, as that will cause a reaction and remove the coating itself.
If it was me, I would personally opt for the silver iPhone X with the stainless bands, and you can polish the bands whenever you feel it’s necessary. (And you won’t have any tarnishing with surgical stainless.)