Tokyo Ghoul isn’t a fighting anime, there’s no tournament of power, there’s no eyepiece that measures power levels. There aren’t even really any duels. The fighting that goes on is strictly serious. In a series like Dragon Ball, we see Goku and Vegeta constantly sparring against each other to measure their power. In Tokyo Ghoul, there’s nothing like this. People fight out of necessity, not out of sport, save for a few unsavory characters. So it can be difficult to determine who is the most powerful. Yet the question remains: Is Kaneki the strongest ghoul? And if not, who is?
Full Summary and Analysis of Kaneki Ken
What makes Kaneki Ken so strong is his troubled past. He begins his life as a normal human yet he suffers as his mother continuously neglects him. Subconsciously he blocks out these memories yet they seem to always hold him back. He lets people walk all over him and has difficulty asserting himself. These problems continue after Kaneki has Rize’s organs transplanted into him. As a man stuck between two worlds, he loses his membership in both. Kaneki struggles with a major identity crisis that challenges the sheltered worldview he has created. The problems from his past, that he has suppressed for so long, finally come to a head when he is kidnapped by a sadistic ghoul named Jason.
This ghoul relentlessly tortures Kaneki as an outlet for his past trauma (as you can see trauma is a common trope throughout the series). These actions force Kaneki to confront his point of view. His mother always taught him to accept the pain that others inflicted on him. It is better for him to get hurt than for the others around him to be hurt. Kaneki finally realizes that he is tired of being on the sidelines in his own life. He wants to be strong to protect himself and his friends. He breaks free from Jason‘s imprisonment and in doing so he consumes him. This represents Kaneki’s first step in becoming a Kakuja and becoming one of the strongest ghouls.
After Kaneki’s realization, he becomes obsessed with becoming stronger. He abandons the people that were so important to him in a fruitless and misguided attempt to protect them. In doing so, he effectively loses the people that he was so desperate to keep close. Yet, in doing so he continues his cannibalistic tendencies. This makes him physically stronger but stresses him mentally.
Kaneki continues on his quest for power until he is finally confronted by the fruits of his endeavors. He sees his friend Hide mortally wounded in Anteiku. This leads him to recklessly challenge Arima (the strongest ghoul investigator). Kaneki is resoundingly defeated and has his brain punctured through both eyes. Any other ghoul would perish from such an act but Kaneki’s otherworldly regenerative abilities allow him to live on. Unfortunately afterward, Kaneki is thrown into Cochlea as a prisoner. During his incarceration, Arima tortures Kaneki by telling him that all of his friends are dead. This forces Kaneki to disassociate himself from reality until his personality is changed and he takes on the name Haise Sasaki. This crucial part of the story is left out of the anime and can only be found in the manga.
During his time as Haise, Kaneki’s power is considerably weakened. He has no memory of his friends or his previous life. Much of Keneki‘s powers are derived from his traumatic upbringing and past. As Haise, he is unable to tap into these motivators.
Eventually, Kaneki regains his memories. This happens during the CCG raid on the Tsukiyama family. Kaneki goes on to defeat Arima who kills himself as a result. After this, no one can match Kaneki’s strength. Eventually, he is driven to the edge after seeing Touka surrounded by enemies. As a result, His Kagune expands to destroy all of Tokyo. After emerging from his expanded Kagune (known as the dragon) Kaneki defeats Furuta and solidifies himself as the strongest character in Tokyo Ghoul
TLDR summary of who is the strongest
If you didn’t feel like reading all of that (I really encourage you to do so) Kaneki is certainly the most powerful character in Tokyo Ghoul. He single-handedly destroys most of Tokyo and confronts the strongest characters in the anime. He becomes so strong through his trauma and desire to protect his loved ones.