Espeon Fan XD
I would say Espeon, I liked him ever since he was shown in the 2nd gen. Heck he is even better in 5th gen with the his DW ability. But I will say Umbreon does have his charm though. I really like his shiny version, but as an overall pokemon. I still chosse Espeon, there is just something about the way it was made and how it looks like it is hiding something XD
Also it's a psychic version of eevee, which seems to be a pretty popular typing, given mewtwo's popularity. I personally don't care that much for psychics, I'm more of a dragon fan ^^ But I do have a few favorite psychics, like Espeon, mewtwo, alakazam, and a few more. But yeah, espeon is just mysteries.