Originally Posted by
Grizzlokk
It's hard to develop a true BiS for healing Priests, since many of us have different opinions on the level of Spirit we need or what the better stat is (Haste / Mastery). This is probably why you haven't seen many healing Priest BiS lists.
However, it would be very easy for a Holy Priest who wanted to stack Mastery as a primary secondary stat to come up with their recommended BiS list. As an example, this would probably use the offset chest piece from Halfus with the helm/shoulders reforged for Mastery. Picking up all Spirit / Mastery items you can (including heroic versions of the somewhat-rare Conclave drops). Heroic Fall of Mortality / Shard of Woe for trinkets, and finally filling any slots that don't have Spirit/Mastery drops with Haste/Mastery items.
Then again, some people choose Haste... So now you have to start over. There's really no such thing as a true BiS list with the current state of Priest healing since it varies so much. Just get Spirit to a comfortable level, stack Haste and/or Mastery, and get better more Intellect through higher item level drops. That's as close as "BiS" as you will get for Holy.