I Wanna Be Your Lover and Don't Stop Til You Get Enough

but really it's never been about the music. it's about the fact that they each crossed over to Pop around the same time - 1983 to 1985. Prince 'dethroned' MJ in 1984 when Purple Rain and its associated mania 'took over' after Thriller mania calmed. Prince and MJ were among the first Black acts to have videos aired on MTV. the comparison is rooted there - in the promotional campaigns for Purple Rain and Thriller (plus Victory and its tour), IMO. it's not about anything else.