Imp Devotion Aura 99% of the time. Tanking seal is SoV once you have it, SoR until then. Blessing of Sanctuary should be keeping you in mad mana at higher levels, and at lower levels it's rarely an issue.

Remember that your tank isn't there to do damage, it's there to keep damage from happening to your other members. What level are you at? If it's high enough to have Holy Shield, you should be able to hold aggro without too much effort. You've got Righteous Fury up, right?