Majora had absolutely zero development. All we know is that he/she/it is a demon whose power was sealed inside the Mask by an ancient tribe. Majora is nothing more than an evil bloodshed-hungry demon who wants to destroy the world for absolutely no reason. If anything, Skull Kid is a more interesting villain than Majora because he actually has a backstory and his actions/pranks were just influenced by the power of the mask until the mask finally took control and decided to become a generic villain.
All these Majora origin/personality theories (Stone Tower theory, the Moon, boss design, etc.) are ridiculous and are built off of extremely minor, completely speculatory, and almost baseless assumptions. I see absolutely no reason to believe Majora is the greatest Zelda villain, let alone a good villain in general.