Well thats part of why im stuck between Umbreon, espeon and vaporeon. They all have huge color changes. But also, Vaporeon has always been a good tank for me, great stats and a good movepool. I used to always have a vaporeon with me. Umbreon is my favorite so I'm always inclined to choose it. And I already have a lvl90 sylveon, so I don't think I'm going to double up on that, not to mention I'm not fond of the shiny color change, they just changed the pinks and blues around lol.
Shiny umbreon is so rad, grey body, yellow instead of red eyes and those blue rings.... gah. BUT a green espeon??? Come on. But then again, Vaporeon IS pink... I'm so torn :(