Siver has been my favorite skier for a bit so I may be biased but it seems like he's maxed out technicality when it comes to rails. Sure there's dudes like Henrik, B-dog, Jesper, Lj, WW, etc who bring a ton of creativity into the mix but as far as straight up slaying rails, I think Siver is top dog. If you haven't watch his season mixtape he just released, do that first and get back to me.
Have a great season !