Here are my ratings for the Eeveelutions.
1st place: Umbreon:
Umbr30n's rating: 10/10. My favourite Pokemon. Great Defenses and HP. Looks cool. A lot. Umbreon for the win!
2nd Place: Flareon:
Umbr30n's rating: 9.88/10. This was a hard decision, against Jolteon. But good Attack! Flareon also had the better design.
3rd place: Jolteon:
Umbr30n's rating: 9.63/10. The need for speed, getting one of these is a literal shock. However, not very good HP and Defense. But good, but not as good as Flareon.
4th place: Glaceon:
Umbr30n's rating: 9.04/10: This is where ratings stumble down. Sure, Glaceon can look cute with good Special Attack and stuff, but many Ice-Types have bad Defenses PLUS only a resistance to Ice.
5th Place: Espeon:
Umbr30n's Rating: 8.26/10: Same with Glaceon. Many Psychic-Types have bad Defenses, but this is one of the Eeveelutions that rely on Speed! Speed isn't useful if you have many, or if you have few (I'm not talking about Umbreon speed there).
6th Place: Vaporeon:
Umbr30n's Rating: 7.55/10: Well, this one IS good with HP, but I think this one would be used for battling the least. Hydro Pump and Ice Beam are useful picks, however.
7th place: Leafeon:
Umbr30n's Rating: 5.89/10. Well, it's good that they had a Grass Type evolution. But the elemental movepool. The HP. Where are they? Let's not even jump to the Looks-Like-A-Digimon subject. Other than that, it's "Quite" a good Eeveelution.
But these are my ratings. You're welcome to share your own.