Off the Wall is generally considered MJ's best album, but I don't really agree. I think Thriller is definitely more cohesive, and Dangerous seems to strike the perfect balance between being sonically innovative, creative, and vocally gritty but still bright in some spots. As for Invincible... I don't know, it's not as crazy of a take as some people are making it out to be. Invincible is still a really good album that gets shit on unfairly, I think. It probably really boils down to if you like disco or not. Someone mentioned that Michael's vocals are better by Invincible, but objectively that's just not true. The autotuning on the beginning of Butterflies wouldn't be necessary for Off the Wall era MJ.
Off the Wall, Rock With You, Girlfriend, and It's the Falling in Love are some of the best songs Michael ever recorded. On the flipside, Invincible was a super innovative album with a very unique sound (industrial r&b?). Heartbreaker is something like glitch-pop and a precursor to what would become dubstep--whether that's a good or bad thing on the other hand... Anyway, I think Invincible's mainly bogged down by unnecessary tracks. Songs like Unbreakable, Break of Dawn, You Rock My World, and Threatened are some of the best songs in his catalogue, while songs like Speechless and the Lost Children are among the worst (Cry isn't that great either). But then, then the outtakes make up for those: She Was Loving Me, Escape, A Place With No Name, Blue Gangsta... Seeing Voices, all of these are amazing.