We'll have to wait and see whether Spark being High actually hurts Baraka or is of no importance to his core gameplan. I won't deny I'm a little worried but I don't like to fully panic about a character being bad before the game is even out so we shall see after release.
Oh and to answer the question it's the everything: The Personality, The Fresh New Moves, The Classic Moves, The gameplan with his KB's that seems to invite patience and punishment, His VA who went from voicing one absolute favorite of mine to the other, The Gear Options we've seen.
Put simply I'm in love.