Lol arguably the strongest character is from that series.
I don't like how the characters power levels translated into that sequel so I dropped it after a few chapters.
AP is attack power? I feel that, for example, Naruto from the end of Naruto, even before he received the powerup from Rokudou Sennin, was an absolute beast. He made an infinite amount of clones and had all of them doing chou oudama rasengans everywhere while in full control of the Kyuubi.
His AoE is immense, but I have serious doubts for it's actual strength and efficiency against a single but overpowered individual from Bleach (both because of speed and because of resilience). Also, I feel like Naruto suddenly forgot how to make at least half of what he was doing in that war when he became an adult, instead of growing stronger, so I feel like picking his original Naruto self is making him a favor.
I can see Naruto taking down some of the Espada and some shinigamis, but not some of the Bleachtoptiers, and I don't see other heavyhitters from Naruto like Rock Lee / Might Guy defeating Zaraki. Not even Itachi. He can drag him into a tsukuyomi or whatever, but Zaraki cut his way out of an outerspace pocket dimension that wasn't an illusion but a genuine "creation" power.
What do you think?