Funny enough I'd say GX probably did the best overall in terms of treatment of the side-cast, even if it would inevitably turn into the Judai show a lot of the time. Certainly had the biggest amount of strongly portrayed side-characters at the very least. Even Manjoume got a W over Edo at the end, Sho inherited the Cyber Dragons, Ryo has one of the best duels in the franchise, Austin drawing against the Supreme King, Johan in general etc. It was pretty good, except for Asuka not really getting much post-Season 2 but again it's Yugioh, we have to take what we can get for the ladies.