I really enjoy being a sith, be it an Inquisitor or a Warrior. I enjoy the playstyles, but it's the interaction with the NPC's that really make it interesting.
Both my Sith inspire fear, respect and more fear. When quest giver speak to my Siths (I don't know what the plural for Sith is) they apologize for existing, for daring being in the presence of magnificent me. Even the Inquisitor, who used to be a slave, is now treated with all the respect she deserves. Because they know she could end their miserable existence without breaking a sweat, and there's actually nothing she'd love more than to do just that. And they thank me for letting them live.
And I especially love the NPCs that think they can beat me, the look on their face is priceless when I slice them into pieces.
On the other hand, when I'm playing my bounty hunter, most of the quest giver treat me like shit. But it's fine, because I get credits for my work, and I could care less what they think of me. And if they piss me off, I can use 'em as targeting practice. (Mako would sulk for a while if I did that, but nothing a nice gift wouldn't fix.)
Anyway you look at it, I always win.