I know they are converting crit to parry but they're also adding Attack power based on mastery (Unsure if this is still around/being kept)
So...Mastery will give us mitigation AND damage? Sign me up.
From my napkin math (aka: completely off the top of my head) you're basically just going to want crit/mastery everything with a focus on the latter with gemming for mastery (I guess).
It's really very situational. With the rage income you have since they added riposte and crit rage, you should be doing a lot more than just spamming shield block. Shield block will of course be very strong at the beginning, as it always is, because it doesn't need vengeance/resolve to prop it up.
Barrier is of course still extremely strong and will be the go-to mitigation at high vengeance levels, and they should be weaved in even at low gear levels.