Which chest piece do I choose as unholy?

[Phizickz]

I recently coined the Breastplate of Shamanic Mirrors (crit/mastery) from Dark Shamans HC, but the problem is that I already have the Chestplate of Congealed Corrosion (crit/haste) from Immerseus HC. I am quite new to unholy, and even after the recent hotfix I am not too familiar with the stat-prio. Which chest would be best to go for? (neither are warforged, obviously)

[Soisoisoi]

Whichever has better stats for you? Fairly sure Crit > Mastery > Haste is the way to go for Unholy, so on a whim I'll guess Shamanic Mirrors. Just use stat weights and see what's best - or use Askmrrobot since that's probably easier.

[Deleted]

If you are fighting your enemies and suddenly realize "darn I violate my buttons with all i've got yet there is nothing I can do" you might wished to equip the immerseus one. If you had a very clean fight and watch dps meters, jealous of the warriors and so on you might regret not equipping the dark shaman one. So... do you believe in math and have forsaken the world or are you simply on the edge of insanity?

[Raikh]

The difference is very small and if shamanistic mirrors is a dps gain is also a question of your whole gear set. All stats are pretty similar for unholy in strength, if you have much of one the others are likely to get better than the stacked stat at some point, crit is just a bit better than haste/mastery for a higher amount of stats, but it is technically no blindly reforge to that answer.

Would go with the statement above, if you "feel" that you could have less haste take the shaman chest, if you feel you could maybe even take more take the immerseus one.
Fro the sake of mathematicals tuff shamanistic mirror is listed as BiS for unholy. (you could reforge the haste you want from elsewhere also)