From what I am seeing WHM are the best when it comes to MP management with powerful heals and considerably more DPS for clearing. I have seen tanks do pulls that an AST would barely be able to heal through without issue cause the mobs stay stunned for the majority of it because of the WHM holy bombing everything to death. In a way its rather absurd, not that I mind. When on my RDM I only ever have to mana transfer a WHM if they somehow died and I had to get them back up. ASTs though? I have to mana transfer on cooldown basically because they are so MP starved from what I am seeing.

SCH though definitely needs buffs from what I am seeing, they have just about died off.