I think it depends on what kind of story you enjoy. For example, I've read a few times that the Trooper had an excellent story. But I don't enjoy "soldier stories," so them going on about me being in an elite unit or my first companion talking about his past in a different elite unit or all the military banter made me want to spacebar past the dialog. For me, I enjoy stories of healing or redemption so the JC story (only in Act 1) has been good so far. I'm curious to see how Inquisitor is but in the first 10 levels it seemed my options were along the lines of kicking puppies or just plain setting fire to them. I hear the Agent story is excellent as well so that might be the next Imperial story I'll attempt.