I liked light for ages, I even admired his thought process, determination and ability to get people to do as he wants, but when he manipulated his own father leading to his death and didn't shed a real tear, I began not to like him, when he started cheating on the girl, whatever her name was, I went off him, cheating, as a victim of such an act, is unforgivable.
Sasuke, has changed a lot over the story arcs, he used to be really smart, now he's not, he's just a tool for the first Uchiha and his plans for the village of the leaf.