Originally Posted by
[-Spiritus-]
Good lord, Sanctuary is an HPS booster. Think of it this way. AA is a 15% boost to all healing for 18sec, the same duration as HW:Sanc. That means 480,000 hp must be healed in that 18sec, or 26,667 HPS, to equal the output of AA in the situation you describe (which is admittedly ideal in a 10m setting).
That being said, both have positives and negatives. Pluses for Sanc is that it requires only a .5sec set up and does not require additional casting for the boost. Negatives are mana cost and positioning requirements. Pluses for AA is a very low net mana cost (HF+4 smites is still greater than 5% mana, even with Evan [though the atonement healng makes that burden null, assuming you have a period to build the stacks]) and no positional requirements. Negatives are ramp up time and the requirement of the boost to be connected to HPS.