According to Elitist Jerks:
"The best trinket currently available is [Darkmoon Card: Volcano]. For second place, [Heart of Ignacious] and [Theralion's Mirror] are very close. The Mirror tends to look better on paper, although there can be advantages to an activated trinket (as opposed to a proc). [Bell of Enraging Resonance], [Witching Hourglass], and [Stump of Time] are also good."
I couldn't help but notice no mention of [Soul Casket], the valor trinket that is 321 mastery (which we would reforge to haste) and a 2min CD for 1926 spellpower for 20 secs. Mastery sucks for us right now, but with the next patch right around the corner, mastery will be buffed to be better than crit. Not to mention how powerful on use spellpower trinkets can be in the right hands. Im wondering where exactly this forgotten trinket would rank up? They also didn't mention the jewelcrafting trinket [Figurine - Jeweled Serpent]! I would hate to take a trinket from another caster if one of these trinkets would actually benefit me more.
I also want to mention, [Darkmoon Card: Volcano] is absolutely amazing! When it procs, not only do you do awesome threat-pulling damage, but you can innervate an oom healer to almost full mana thanks to our innervate scaling with our base mana pool!