>>22776298Both are good, stop trying to piss onto something without thinking about it first.
Sylveon is stronger, but only when you lock it down to one move, which makes this pokemon realy predictable.
M-Gardevoir may not be that strong, but it has a big coverage of moves, STAB Psychic, better speed and isnt locked down to one move.
It all depends on preference, want to be stronger or more versatile.
And if you aren't a smogon fag, looks and background story, etc. will be the deciding factor