How far critical strike has fallen
At one point in early Wrath, critical strike rating was one of the most powerful stats for a holy paladin. Illumination was our key mana regeneration mechanic, and stacking crit was a great way to boost both throughput and longevity. I remember how excited I was when I won the roll on a Soul of the Dead, the ultimate mana regeneration trinket. Glyph of Holy Light also worked well with critical heals, as both the initial heal and the subsequent splash could be critical strikes. Critical strike was an amazing holy paladin stat, and we actively sought it out on gear.
Critical strike chance is now our worst stat. Its decline was slow but definite. The disabling of crit on Glyph of Holy Light's splash was the beginning, while the gutting (and eventual removal) of Illumination was the end. Without Illumination giving us back mana on critical heals, crit's only value comes from its boost to our throughput. It doesn't boost our throughput as much as haste does, and it provides no longevity improvements. Whenever you start ordering stats, there's always going to be a stat is the worst. Unfortunately for crit, it finds itself at the bottom of our list. Unfortunately for us, we find it on three pieces of our current tier set.
Spirit is the key to longevity
For every action, there is an equal and opposite reaction. As critical strike's value has hit rock bottom in Cataclysm, spirit's stock has skyrocketed. Meditation, one of our holy tree bonuses, allows us to regenerate our mana via spirit while in combat. Previously, spirit would literally give us zero mana since we were constantly casting heals. Since mana per 5 was removed, spirit is really the only regeneration stat in the game. If you are on a fight that requires a lot of healing, spirit is the secondary stat you want to bolster your longevity. Spirit even allows us to regain more mana via Judging when Seal of Insight is active, as Enlightened Judgements lets spirit help us hit more often.
I like to think of Divine Light as the healer version of Life Tap. Instead of trading health for mana, we can spend extra mana to drop bigger heals. Because we're able to change our throughput by adjusting our mana usage, spirit has the secondary effect of boosting our throughput, but only when we want it to. Having more mana gives us more options, and since we're never at risk of not having enough throughput due to our flexible healing models, I find myself preferring spirit over all other stats.
Haste is the throughput stat of choice
Holy paladins previously had essentially three heals: Holy Light, Flash of Light, and Holy Shock. Haste obviously affected all three of these heals by lowering their cast time and reducing the global cooldown, and so it was easy to see why it was so valuable for us. Haste continues its reign at the top of the throughput list. Holy Radiance actually scales incredibly well with haste, just at defined breakpoints.
Our healing spells have had their cast times increased in Cataclysm, and haste helps us restore some of the reactivity that we lost from Wrath's near-GCD cast times. If I could only have two stats, I'd pick haste and spirit. Haste lets you use your spells more often, while spirit lets you keep casting them. The combination is currently unbeatable.
Mastery isn't great, but improving
While I've talked about our current mastery bonus, Illuminated Healing, Blizzard has been consistently buffing it on the patch 4.1 PTR. The scaling of mastery rating was improved by 20%, and the duration of the absorption bubbles was nearly doubled. I plan on trying out a mastery-based gear setup once patch 4.1 makes it to live servers, if only to see how effective it can be. Blizzard is clearly dedicated to making mastery desirable for us, and so I'm interested in seeing how potent Illuminated Healing will be after the changes.
With haste and spirit easily winning the secondary stat war, we will be primarily reforging out of crit and mastery. I suggest checking out the Holy Radiance haste chart and seeing if you're near a haste breakpoint, then reforging to haste if you can score an extra tick. You're not going to be able to find haste/spirit pieces for every slot; there's simply not enough healing plate gear out there. I simply reforge to haste or spirit, whichever happens to be missing from the gear.
The Light and How to Swing It: Holy helps holy paladins become the powerful healers we're destined to be. Learn the ropes in Cataclysm 101 for holy paladins, study the new balance between intellect and spirit, and learn how to level your new Sunwalker. Tanking is a job, DPS is a craft -- but healing is truly an art.