Who has gone the most OP in their Youth?

[Lilvic92]

Obito - mokuton, kamui, control of the kyuubi and yagura (3rd Mizukage)

 

[redsglory1974]

rock lee

 

[Fanta]

Itatchi or Nagato.

 

[TheCCV]

Nagato, Tobi and Kakashi.

 

[Drakengard]

If the Obito that killed those mist ninja/fought Minato counts then I'd have to pick him over the others listed.