I'm having a hard time finding a confirmed stat priority for priests (holy and shadow specifically).

Currently my "wish list gear" is basically any cloth piece that has spirit and haste (I'm trying to make a set that works seamlessly for both holy and shadow, but I'll eventually work on two sets. I'm trying to let the non spirit cloth go to non-spirit casters.)

I've seen the effect mastery has had on the damage I do, but I am not sure where it falls in relation to haste. According to the numbers I've found, it was less useful than haste, but it seemed to be the pre-change mastery (although the thread was super long and may have been updated since). As per the gear list stickied on these forums, mastery is more preferable on some of that gear, but it seems a bit of mix there, so I don't know what to take from it.

As for healing, I'm kinda hesitant to go for mastery over haste. Without a metric ass-ton of mastery the extra HoTs just don't seem worth it.