If it's not Espeon, I will cry. I mean, let's look at it logically. Gary (or whatever his name is XP) has an Umbreon. They won't have two Umbre's, right?
Jolt, Vapor, and and Flare? Pikachu is an electric, and Jolt doesn't fit with May (well, neither did Combusken, but...). As and Brock have water types, so the team doesn't need another one. Combusken is a fire type, so Flareon's out.
That leaves Espeon! And, really, it's a girly Pokemon, and May is all girly with her Pokemon choices (Skitty, Beautifly...)... Yay, Espeon!
-Edited to change a typo. Literally. I had 'type' written as 'typo'. I'm a moron.-