I grew up on the J5, but came of age with Prince. I was a BIG Prince fan! (I still have my 1999 concert t-shirt!)
I never thought there was a rivalry. Each did his own thing. Each had his share of copy cat artists. (Even Rick James wanted to be Prince. Remember Process and the Do Rags and The Mary Jane Girls? And if his Glow video wasn't a four-minute bootleg version of Purple Rain, I don't what was.
Back in the day folks thought Prince was a weirdo, a freak. Nowadays some folks use the same words to describe MJ.
Anyway, my all-time personal favorite is Prince.