WD, MND, VIT, and defenses pretty much trump all else.

That being said, when the choice presents itself, I favor DET/PIE for both WHM and AST, CRT/DET/PIE for SCH.

Spell Speed thus far doesn't seem to grant a large enough boost to HoTs to compensate for its relative uselessness for healing purposes. Spell Speed does offer something for DPS (both for hard-cast nukes and at least to some extent for DoTs now), but IMO it brings very little to healing if you already know when and what you're supposed to be healing.

Crit is great for SCHs because of Adlo, but for the other healers it's...ok. Not that anyone has much of a choice at this point due to limited gear options, of course.