The best is what you like most and what does the things you want to do with it.
Better read through the hits from https://www.google.com/search?q=asus+zenbook+linux for useful tips.
I am pre-purchasing ASUS ZenBook UX306UA, which comes with win 10. I intend to delete all partitions on the SSD and then install Linux on "clear" SDD. What would be the best distrubition of Linux for it? Ubuntu or Mint maybe?