Please give in-depth reasoning to your answers, i.e haste for quicker casting of greater healing wave, meaning more time not casting, which means more time where 100% of your spirit can be used to regenerate mana.

I personally think the most important stats, in no particular order, are spirit intelligence and crit rating. People seem to think though that haste is of greater importance than critical hit. I fail to see why.

Spirt-faster mana regen
Intelligence-more mana