pizza is right though haste is individually the best stat right now for boomkin, if you had to pick ONE, although i dont agree with full haste necessarily unless youre using it to maximize your utility by maximum dot/rejuving spreading everyone who needs it (cuz with full haste build's shortened gcd's, this is really no difficult task)
realistically haste & crit should be better than vers though, you really never get anything that great out of vers in a game on most things right now besides melee that already pick & choose when they want to rape (rogues, ferals, arms warr)