The best designed Ice? Sneasel came to my mind first (I'm not Weavile's biggest fan), but you know I think Articuno, Glaceon and maybe Dewgong can come up there.
Glaceon doesn't really have all that great of a design to me, but I've seen a lot of fan depictions which kind skews the appeal. Articuno is one I've ALWAYS loved. I can remember being 5-years-old and saying it was, like, my favorite. It still is one of them. Dewgong's design is simple yet effective. And Sneasel just looks really unique as an icy weasel thief with a feather thing xD
So tie between Sneasel and Articuno.