1: Uchiha Madara: Madara's Mangekyou Sharingan ability, Kamui, is a mystery. His Susanoo is unique as he can use it without Sharingan, overpowering the Nine-Tails and Five Kage. Madara's Mangekyou Sharingan abilities are the strongest.
2: Uchiha Obito: Obito's Mangekyou Sharingan ability, Kamui, is a powerful space-time ninjutsu, even with one eye. With both eyes, his attacks penetrate anything. He withstands Kaguya and Momoshiki. Obito's Sharingan is one of the best.
3: Uchiha Itachi: Itachi's Mangekyou Sharingan abilities are Tsukuyomi and Amaterasu. Tsukuyomi is a powerful genjutsu, while Amaterasu is an unstoppable black flame. Itachi's Sharingan is not weak but his overall ranking is not high.
4: Uchiha Shisui: Shisui's Mangekyou Sharingan excels in genjutsu but lacks overall ability. His Kamui has long cooldown and is inconvenient. Shisui's Sharingan is ineffective against powerful foes.
5: Uchiha Sasuke: Sasuke's Mangekyou Sharingan has Amaterasu in his left eye and flame manipulation in his right eye. His abilities are limited to Amaterasu. Sasuke's Sharingan alone is not enough without Rinnegan and Six Paths power.