>>12793953I didn't 'pick' a favourite.
I saw Espeon and was struck with a sense of "I fucking love that design". I've never felt the same since.
Several ways to pick:
Go with whichever one is your favourite type, or whichever one has the type you like the most.
Consider the themes of each (as in, actually read Pokedex entries and consider what themes/personalities fit each), and pick the theme which either matches you best or is your favourite:
>Vaporeon can be water, invisibility and elusiveness;>Jolteon can be lightning or danger;>Flareon can be fire or warmth (including emotional warmth);>Espeon can be the mind, ESP and the sun;>Umbreon can be darkness, night and the moon;>Leafeon can be nature and purity (see its Pokedex entry for Gen IV);>Glaceon can be ice, can also tie in with exploration;>We don't know much about Sylveon yet, but it could be ribbons, joy, mythology etc>if you want to include it, EeveeThe themes are open to discussion, considering the above are just suggestions.
Tying in with the above, think of a Gym you'd like to be leader of and give it a theme or challenge (dreams, mazes, riddles etc). See if this theme fits in with any of the above. For instance, a basic theme like the moon or dreams would probably fit with Umbreon; a mythic/fantasy theme would fit with Sylveon; and so on.
You could also consider what personality each would have, either based on the images posted or on interpretations of its type, dex entries etc. Either:
>Pick the one matching your personality>Pick the one that has an opposing personality - you can balance each other out>Pick the one with the personality you find the most desirable, i.e. in friends>Pick the one with your least desirable personality so that things are more interestingBut since you're having trouble deciding, I'd argue you can just go with Eevee.
Remember, Eevee itself hasn't decided either.