Depends on the fight. On Malygos or Sartharion (w/drakes) where Magic damage is everywhere I would go with the stam trinket. On a more physical fight I would probably take the Defender's Code, I really like the massive Defense on it since it spreads it around and you get block rating out of it too. The click ability is pretty nice, and can also be useful on things like Sartharion where you need as much HP as possible (if you are taking his breaths while you have a nasty combo of drake debuffs up).
Just depends really.
Of course if you need the Code to stay crit immune use it.