Uchiha Itachi
What is wrong with these passages?
He graduated top of his Academy class at age 7, had mastered the Sharingan by age 8, became a Chūnin at 10 and was previously a Black Ops (ANBU in the Japanese versions) squad leader at the age of only 13. He left Konoha about five years ago, after killing off his whole clan except for Uchiha Sasuke, his little brother. At 17, he was even feared by Orochimaru. He is now currently associated with Akatsuki. Orochimaru had planed to use Itachi's body as a new container, but seeing as Itachi is powerful to such a degree that even Orochimaru fears him (Possibly for the ability to copy every single jutsu he ever obtained with the sharingan) and has stated that Itachi is stronger, it's easy to see why Orochimaru decided to leave Akatsuki and try his luck with Sasuke instead.

Or,
 There have been many debates between fans whether or not Uchiha Itachi is the most powerful shinobi in Naruto, commonly comparing his power to that of the Legendary Sannin. Nonetheless, common sense might point to Akatsuki Leader being the strongest, Although that cannot be known due to his/her rare appearances.