Michael Jackson was infamous as well as famous. There was a lot of stuff that went into his fame, including starting out as a heavily produced child act.
Prince, in my opinion, was a much more talented individual but he didn't live the same kind of public life as MJ.
However, don't discount Prince's popularity during the Purple Rain period. He was massive and "When Doves Cry" was a smash.
That he also wrote a bunch of songs like Jungle Love, Nothing Compares 2 U, and Manic Monday that became big hits for other people just shows how much depth he had as an artist.