I have been reading Sub is the best for single target, but takes more attention to play than Assassination/Combat and may not be the best choice for a returning player until you know the fights in HFC.
Then I have been reading Combat is the best spec, because a lot of fights in HFC are AoE-based, and only a few like fel Lord are single target.
Then I have been reading Combat is the worst spec, behind Sub/Assass.
What's the real deal here? What spec is supreme?
Are all 3 specs viable? How big of a difference are they?