Both have their share of pros and cons but Titans has a slight edge just because of krypto. Though I do feel that titans's Conner was a little different in terms of his personality from his comicbook counterpart. The rebillious 'punk' nature that Conner displayed when he first got out was missing from the titans version of Conner and smallville's Conner was straight up evil when he first escaped but in terms of story and character development, Smallville takes the cake. Conner is also in the titans on smallville's earth, infact, he's the the leader there.