i would say there is no best spec and it heavily varies per encounter. for instance on spine of deathwing assasination is the worst of the 3 specs and i'd rather be a sub on that fight . on ultraxion sub is plain bad while combat and assa take the lead. Now i would advise having either combat or assasination on one spec and a subtlety spec as offspec :D be warned tho sub takes the most skill of the 3 >_>
