If there was an all out fight between Naruto and Sasuke, who will win? Basically, who is stronger, Sasuke or Naruto?
This will create a long debate. However, it is mentioned multiple times throughout the series that they have equal strength. Naruto knows this by exchanging fists with Sasuke, he specifically tells that to Sasuke in the Shippuden episode (spoiler alert!):
Where Sasuke kills Danzo, and then goes after Kakashi by almost killing Sakura
In the end of the series, Kishimoto gives an answer to this:
Naruto and Sasuke have an all-out fight to death because Sasuke believes in order to protect the world from evil, he has to cut all emotional ties. And, quote Sasuke, "[Naruto] you are my only friend". This battle ends with both of them losing an arm, and heavily bleeding until Sakura saves them.
It is implied that they both have equal strength.