Tobi, Itachi, and Orochimaru have all stated that Sasuke possesses the unique potential to become much stronger than Itachi, who was already considered a genius above all others. Orochimaru even mentioned that Sasuke is stronger than the former was at the same age, when he was training Sasuke in Part II of the story. Tobi has also stated to Zetsu that in time, Sasuke could become more powerful than Nagato.
Nagato Uzumaki
As the leader of Akatsuki, and one of the two sides of the Amegakure civil war, Nagato was an extraordinarily powerful shinobi, and recognised as the most powerful member of Akatsuki. It has been noted at several points in time that Nagato possessed an unusually large amount of exceptionally strong chakra, to the point of after he decimated Konoha and fought Naruto Uzumaki, he still had enough strength to revive all of the people he had killed in Konoha. His partner, Konan, had stated that he had never lost a single battle, and that he is "unbeatable".
Uchiha Itachi
Even at a young age, Itachi's intellect and talent showed their brilliance in everything he did, as even his teachers said his progress hardly required any help. In the few battles he had been seen in since the start of the series, Itachi was shown to be an incredibly powerful ninja, as demonstrated by his ability to easily defeat several powerful shinobi. Despite his pride in his own strength, Kisame Hoshigaki, Itachi's partner in Akatsuki, acknowledged Itachi as the stronger of the two. Tobi said that Itachi never ceased to amaze him.
I got all of this information from Naruto Wikia..
Nagato Uzumaki
As the leader of Akatsuki, and one of the two sides of the Amegakure civil war, Nagato was an extraordinarily powerful shinobi, and recognised as the most powerful member of Akatsuki. It has been noted at several points in time that Nagato possessed an unusually large amount of exceptionally strong chakra, to the point of after he decimated Konoha and fought Naruto Uzumaki, he still had enough strength to revive all of the people he had killed in Konoha. His partner, Konan, had stated that he had never lost a single battle, and that he is "unbeatable".
Uchiha Itachi
Even at a young age, Itachi's intellect and talent showed their brilliance in everything he did, as even his teachers said his progress hardly required any help. In the few battles he had been seen in since the start of the series, Itachi was shown to be an incredibly powerful ninja, as demonstrated by his ability to easily defeat several powerful shinobi. Despite his pride in his own strength, Kisame Hoshigaki, Itachi's partner in Akatsuki, acknowledged Itachi as the stronger of the two. Tobi said that Itachi never ceased to amaze him.
I got all of this information from Naruto Wikia..
