Mastery is uber for warriors. Reforge everything into it, seek it out wherever possible (within reason - I wouldn't consider using a DPS trinket to be viable no matter how much mastery is on it, unless you're building a threat set).
For that reason I would use the Crab over the Finger, however one could make a case for Impetuous Query being better than both (I don't play a warrior myself, I just read the threads on here that are all like "ZOMG MASTERY MUST HAVE GET IT GET IT GET IT"... so I can't say for sure :-P ).
For heroics you can wear dual avoidance/mitigation trinkets, or one of each - it doesn't make a huge difference, to be honest. Stacking pure stam is, aside from some of the heroic mode raid bosses (or so I hear), not viable. For some of the entry raids, I'd suggest one stam trinket and one avoidance/mitigation trinket. So the Crab (reforged into Mastery) and the JC trinket, in my opinion.
If you really want to drop some cash, you could do what I did and pick up Alchemy for Lifebound Alchemist Stone which is basically the most amazing thing ever. <3 it