The best suggestion I can make is to look at the Tank forums. That said Tenacity has pretty much always been a bottom tier stat for tanks, it replaced Parry a bit too literally if you ask me. Think about it this way, dps stats like Crit and Det also help with your mitigation skills since every tank has a self healing ability. The bigger those numbers the bigger your self healing is. As of right now from what I last read GNB the stat Priority is enough SkS to put you around a 2.38-2.4 GCD, and then Crit > DH > Det > Tenacity. IIRC the DRK and PLD stats are the same with only WAR being the odd one out.