I'm a Michael Jordan fan, but for me he can't be included in any greatest rivalry debate because there was no nemesis, no "anti-Jordan" (though a lot of people certainly are or were anti-Jordan

). It doesn't diminish his greatness, but it does disqualify him from being part of a great individual rivalry. A case could be made for MJ vs Joe Dumars, but that just isn't on the same level as Wilt and Russell or Bird and Magic.
For me, those are the only two choices. I'm tempted to pick Magic and Bird because the wars they waged in the 80s seemed so evenly fought. They met in the Finals three times with Magic's Lakers winning twice, but every series went at least six games. Every Lakers/Celtics game was a big event. They went head to head in All-Star games and even Converse shoe commercials.
But Wilt and Russell faced each other more times than any other two players in the history of the NBA. Needless to say the fact there were less teams in the league during that era is the chief cause for that statistic, but their constant playoff battles coupled with the fact that Russell was seen as the man who could shut down Wilt make it a compelling rivalry.
But then again, it was often the Boston Celtics vs Wilt Chamberlain, "a five man answer to a one man problem". Bird and Magic's battles seemed to feature them as individuals, even though they seldom guarded each other except on switches. This again was probably due to the fact their teams were more evenly matched.
I think I'm going to have to pick Wilt vs Russell though, simply because of the number of times they faced each other in pretty much every possible matchup - regular season contests, All-Star games, Eastern Conference playoffs and in the NBA Finals.