sasuke wasn't a good sith, or a light sith. Light sith were sith who used the light side of the force and thus, casted out by their kin and branded as traitors and for heresy for what they viewed on the force. Sasuke would be best suited as a dark jedi. There are extremely good parallels in between this. Sasuke, from the beginning vowed to kill his brother for revenge against his clan. This is an already dark side trait. He despises itachi for most of his life. After his defection from the leaf, which can clearly parallel a jedi's defection from his or her order.



Sasuke, at the start of shippuden, was never a villain. He actually had morals, having seen orochimaru's experiments on innocent souls and when he killed orochimaru, he expressed disgust at the man for his lack of empathy and life. Comparing this to the jedi's way of life, sasuke at this point would be a grey jedi. He still holds some remnants of his past life and cares for innocent beings, which would obviously fit the jedi's compassion for all lifeforms.



Sasuke, I would say, wouldn't turn completely to the dark until he fought itachi and he fully succumbed to it after danzo. This would be the point to where it can be safely said that sasuke would be a dark jedi