Troll is just too strong and conditional cooldown stacking is what drives the highest parses. Orc would be my second pick and certainly comes close especially if you play with a pet (not sac specs)...just be spot on with mating orc racial to darksoul. Goblin/UD are a notch behind them but still better than generic races.
Supremacy destro I might be orc....pet dmg bonus, haste capping destro (esp w' meta proc), and the 2 min thing might put it on top or very close. Keep in mind that to make trinkets "worth it" on upcoming T16 content their procs will be stronger than our darksoul. (considering heroic tforged T15 ones already push this threshold) Thus reactive dps will be the name of the game. Troll works well for that while orc will fall behind since it relies on pet dmg (never scales as well) and being a 2 minute machine.