As a monk primary, rebirth is good.
Though, as an E/Mo, I have to use Rebirth wisely, as it takes a bit to recharge 70 energy. Though in a tight battle where another player is better than my spells, I will use Rebirth, and sacrifice the energy to res a warrior or monk.
I used Vengeance in PvE a few times just for the laughs when someone just dropped.
