Using empirical research techniques, and scientific method, I.... oh hell... I just checked the rosters for former University of Michigan players. No contest, as it turns out. The Phoenix Cardinals have 5 former Wolverines, while the Steelers have only two, and considering the Cardinals are already the prohibitive underdog, the choice is easy. Go Cards! As a bonus, Alan Branch is from New Mexico.
And Go Blue! I'm sure no other University has, or maybe ever had, that many alums playing in a single Super Bowl!