My personal view:
1. Jolteon, shit has saved my ass many times with its great speed an SpA when played against my friends. I think it also has the nicest design.
2. Umbreon, though outclassed, it's a quite sturdy when you have access to reliable heal in Wish + Protect. Also I love to retaliate with Foul Play when I survive a hit from an opponent with high attack. Design is nice too and he has really deserved a brostatus from me.
3. Vaporeon. Great typing and bulk with acceptable SpA. Design is nice aswell.
5. Espeon. Great speed and SpA and amazing ability. I like cats and it has pretty cute design.
6. Glaceon. Quite shit competitively because ice type with balk, but I really like its design and it is really good ingame.
7. Leafeon. Nice physical attacker with some bulk even though grass is shit offensively.
8. Flareon. Crap competitively even with FB, but damn it has such an adorable design. Fluffy and cuddable.
9. Sylveon. Not saying it's shit or anything, it has adorable design and it is usable (though outclassed, but so are most other, if not all eeveelutions). I just like the others so much more, but this could also be because I haven't got used to Sylveon or something.
