Didn't really like Eeveeloutions that much but then Sylveon came along. Already used it more on PO than any other and it's a qt.
Always been kinda meh on eeveelutions. Design-wise and overall I like Jolteon the most. I barely use them competitively, but Vap is maybe my favourite bulky water in HGSS OU (which I haven't played in ages and wasn't all that great at anyway). Also I feel like pointing out that Leafeon and Glaceon are just bad
Competitevly, probably slyveon or espeon. Jolteon and Umbreon are pretty viable too. Personally i like Glaceons design the most. I dont know why but vaporeons really irritates me