Prince is one of those artists who's catalog of work makes it difficult to have a favorite. If I had to choose it'd be a toss up between the self-titled album and Dirty Mind. But that answer could be completely different tomorrow.
I will say upon rewatching the Batman movie last year I was disappointed with how little of Prince's music you hear in the film.
Also do the Madhouse albums count? Because if that's the case I might have to change my answer...
i say you can count them if you'd like.