Stats were thrown all out of whack by the changes wrought in MoP, but some of our priorities are still the same.
Intellect: Increases the power of our spells, in addition to increasing our spell critical strike chance at a scaling of 3.9469 x 10^-4 crit percentage increase per point of intellect, or 2533.66 intellect per 1% crit chance added. Intellect is our best stat by far as far as throughput goes after haste breakpoints, but given the fact that it no longer increases mana pool size due to mana pool normalization, it has little to no use as far as mana regeneration goes, except for the fact that since heals are more effective, fewer of them need to be cast, thereby increasing mana efficiency.
Spirit: Now our only mana regeneration stat, affects MP5 at the following rate, .5568 MP5 per point of Spirit, or 55.68 MP5 per 100 Spirit, assuming 50% Meditation regeneration rate, all values are adjusted for in-combat regen. Spirit is our best stat.
Haste: Increases spell casting speed, increases the number of ticks that our HoTs get at certain particular values known as “breakpoints,” and decreases the global cooldown for all abilities except Rejuvenation, which already has a 1 second GCD from one of our specialization passives. There are several blogs/sites that have very informative breakpoint spreadsheets, two that I recommend are Earen’s and Theincbear’s. In a couple words, the amounts of haste you should aim for are 3043 to gain the Rejuvenation and Tranquility ticks, and then beyond that 6652 once your gear improves. You should never sacrifice Spirit an undue amount in order to make breakpoints, unless you have no mana problems at all.
Crit: All critical heals now do 200% of regular healing, so crit in general has gotten more valuable. We gain critical strike chance at the rate of 600 crit rating to every 1% crit chance. I generally do not stack crit because I feel it does not mesh with druid playstyle very well, plus, Regrowth already has a +50% chance to crit, which lowers its usefulness with that kind of quick, big healing style.
Mastery: Our mastery, Harmony, functions in 2 ways: First, each point increases our direct healing by a fixed percentage. Then, for 20 seconds after a direct heal has been cast, it buffs our periodic healing by the same percentage. It scales at a rate of 480 mastery for every 1% added to both the direct and periodic bonus. According to Earen, this is an additive bonus, so slightly worse than it looks, but still by far our best secondary stat after haste breakpoints have been met and spirit has been maximized.
In general, stat priority is as follows:
Spirit > Haste to 3043 = Haste to 6652 > Intellect > Mastery > Crit
Addtional Resources to