I'll tell you why Tullius is worse: Because he openly betrays his principles to become an instrument of Thalmor oppression. He knows the Thalmor are the real enemy, but projects his own scheming, self-serving motives on Ulfric Stormcloak. Ulfric is standing up for his beliefs, for his people, at a time when the Empire is letting them be persecuted by a foreign oppressor. How he gets painted as a villain in that context by any rational person is totally incomprehensible.

Yes, he's not the most open-minded and tolerant fellow in Tamriel, and yes, some of his followers are outright bigots. But the Empire has its share of bigots too, and the Thalmor are the goose-stepping Nazis of the piece, and Tullius is carrying their water. As Toby Ziegler put it in 'The West Wing', "You're not the Devil, you're the guy who goes to the corner store to get the Devil a pack of cigarettes".