Oddly enough, I think the honorable thing to do is to complete the songs. As I said elsewhere, Michael hated when his music was issued before it was finished and was brokenhearted when "Hold My Hand" and "Escape" leaked. Now, I don't mean to "contemporize" or rework the song to any significant degree; just take the original demo and flesh out what's already there (unless the song is finished).
For example, all you need to do with the original version of "Loving You" is replace the programmed drums with a live drum kit (since the programmed drums are already clearly emulating a live performance) and it's ready for release.
Sometimes you may have to do a little more, like with "Do You Know Where Your Children Are" (which was knocked out of the park by whoever produced the leaked version). But stay true to the vision and don't impart your own feelings onto the track.
