Umbreon.

Take a look at shiny versions of all the Eeveelutions on Google Images or something. Most of them have terrible color combinations. Umbreon is the exception. Shiny Umbreon is [i]gorgeous[/i].

[img]http://www.gtsplus.net/files/images/art/shiny/197.png[/img]

I mean look at that thing. Such a minor change, yet such a big difference.