So I've been slowly working through all the classes and storylines in SWTOR, and so far (unsurprisingly) the Sith Empire storylines are the most well written, and the best acted. I enjoy the choices you have to make playing Empire side, more so than the Republic side. This is mostly due to two things.
1) Playing Republic side, it feels as though the story writers went out of their way to make things as "black and white" morally as possible. And while that might work in other settings, I think it fails here. Playing both the Smuggler and the Trooper, you get to see more of what the Empire storylines offer in morally ambiguous choices. You can kill/maim someone and earn Dark Side Points, but with that action you actually do more good than harm on a broad scale. Or you could let that same person go free and earn Light Side Points and end up dooming a civilization.
2) The directing for the actors on the Republic side was just too overblown. Especially with a Jedi character, the voice actors are just trying too hard to convey that they have such great inner nobility and purpose...even if you've gone completely Dark Side in all of your social interactions. I actually had to stop playing my Jedi Consular and I deleted the character because I could not listen to the actor's voice any longer. I don't blame the actors for this; I blame the voice director. S/He is the person(s) responsible for such horrendous acting. Shudder.
As it is right now, I'm enjoying the storylines (for the most part) and will continue to play SWTOR for a while until...Neverwinter Online comes out.