I've completed 3 stories; the Sith Warrior, Inquisitor, Jedi Knight. And part way through Bounty Hunter.
I would rank them:
1. Sith Warrior
2. Sith Inquisitor
3. Jedi Knight
If the quality of the BH story continues, I think it will move in to 2nd.
With both SW and SI I felt I had achieved something. It had a "YES!!!" moment.
When I finished the Jedi Knight story I thought "Is that It? How disappointing"