Wick: It depends on your class.
For shield tanks: Mastery is amazing simply because block is 30% of damage stopped. If you can reach close to passive 'unhittable', you will stop more damage than any amount of armor it is possible to get from a trinket. Warriors have critical block, further increasing this benefit.
I use Throngus Finger and Symbiotic Worm as a Prot warrior. The Dodge bonus on parries (in addition to HtL proc on parries) is a decent avoidance boost, and the mastery proc from the worm can save you from a rough spot. Before I got the worm, I was using the Impetuous Query for some additional Parry which would help both the finger procs and HtL.