Here are the trinkets you should look into for in Patch 5.4, Siege of Orgrimmar. I’ve included boring tank trinkets, full dps trinkets, and my personal favorite, the trinkets that land somewhere in the middle. At the bottom I give my best attempt at a “Best-in-Slot” list, if that’s all you’re here for.
Trinkets for tanks are no black-and-white matter. There are trinkets that are good for burst reduction and time-to-live, while others are good for avoidance, total damage reduction, and DPS. Trinkets are the best way to change your stats for what you need at a moments notice, and because of that, there is no true best-in-slot pair. Ideally, you should collect a handful of trinkets with various specialties and swap them in depending on fight requirements.