Season 3, 2, 5, 1, 4, 6, 7, in that order. In the unlikely event you cared. Season 6 has a few truly wonderful things in it, but not enough to compensate for the suckiness of Grinding Misery and the truly stupid take the writers had on what "growing up" means.
Time to go home and work on either this or "Dragon's Heart". Ooh, choices!