Originally Posted by
Totaltotemic
This post is based off of several simulations I ran shortly before the patch came out. Values may not actually reflect live due to adjustments made to the spec between then and now on PTR and various bug fixes.
Crit and mastery are neck and neck in normal gear right now. Personally, I'd go for mastery for its utility in burst phases.
If you add in T15 4-piece, mastery creeps ahead of crit by a bit.
If you use even an LFR version of Rune of Re-Origination, you'll want to organize your stats such that haste is around 5k, mastery is higher than that, and crit is as close to 1 point under mastery as possible. This yields the highest possible conversion to mastery when the trinket procs.