Dude I will be the first to sing MJs praises, I have a Thriller jacket, the album on vinyl, and all of his other solo stuff on cd, I even have one of those Bad 25 Pepsi cans. But heres the thing with Michael, the majority of his best songs were neither written or produced by him. Prince basically wrote and produced everything, and the production level is definitely Quincy Jones level if not better. That being said, i've only got through like 20% of his stuff so far, so who knows.
I'm not going to say he's a better artist than Michael, but I think he may be a better songwriter/producer.
EDIT: im aware saying that michael didnt write his best stuff will probably bite me in the butt. Im specifically referring to the Temperton tracks, but yes he definitely became more active in creation Bad and after.
Not sure about producer, but Prince is probably a better song writer. MJ really isn't that great a writer. I just think the difference between them as performers is so vast that it tilts it all in MJ's favor. He was also just a lot more forward thinking and transcendent for his time.