Bottom line, Dai has a better program and more expressiveness. I think Chan is much more studied in his movements, whereas skaters like Dai and Adam to me move with a lot more natural, unstudied grace.
ETA: I'd agree with you on your above post, museksktr, that's the difference, Chan has a lightness re his blade work, and Adam is not as light on his skates, but he still flows with ease and energy when he's on. And, I still say that Adam has a more natural grace than Chan. Dai is way above Chan in maturity and expressiveness, but in general has some weaknesses in ss. This sp however, is a great one for Dai which highlights his strengths.