This is actually super hard, I love every single one of them. Sylveon is my favorite which is likely no surprise. After that, it goes: Sylveon > Vaporeon > Eeevee > Flareon > All of the others tied(And maybe, if I were forced to arrange them, umbreon > jolteon > umbreon > espeon > glaceon, but I love them still and it's very close). Vaporeon was the historic best before sylveon existed, which was LIKE 10 YEARS AGO.