Since there is hitcap or expertise cap to worry about as a healer I will just keep this simple.
Spirit > Mastery > Haste > Crit. This is the stat order to follow when considering reforging and infact any upgrades where the iLvL is the same.
A couple of examples:
If the item has no Spirit but has Crit and Mastery then you reforge the Crit to Spirit.
If the item has Haste and Spirit, reforge the Haste to Mastery.
If the item has Mastery and Spirit, do nothing.
I'm going to bring up Renew since there seems to be a lot of guides recommending it. I almost never use renew, only on some fights where you are moving a huge amount and can't cast. Good examples of this might be Alakir Phase 1 & 3 or Ascendant Council Phase 2. Neither of these examples justify actually speccing and gemming for it though because it is useless in the other phases. The biggest reason for Renew being poor is that it gets no gain from our Mastery except for Empowered Renew which is a tiny amount anyway. If I am standing still I will never cast Renew and this is the majority of raid time. Renew is also very mana heavy so without Shard of Woe it is going to send you oom quickly even with the recent reduction.