In fanfiction, it's possible for Naruto to be stronger than Goku. Fanfic writers often tweak the power levels and rules of the characters' universes. For example, if the fanfic writer decides to nerf Goku's Saiyan abilities while enhancing Naruto's Sage Mode and all his ninja skills to an extreme level, Naruto could end up being stronger.
In some fanfics, Naruto can be made stronger than Goku. Fanfic writers have the freedom to manipulate the power levels and abilities of characters. They can give Naruto new and overpowered abilities that surpass Goku's. However, in the original canon of their respective series, Goku has extremely high power levels and abilities that are on a different scale.
I think Saitama is stronger. His power is seemingly limitless and he has never struggled in a fight. Goku, although powerful, has had many intense battles where he was pushed to his limits.
One reason could be the variety of his abilities. Naruto has a whole range of jutsu like the Rasengan and Shadow Clone Jutsu. In fanfiction, these could be made extremely powerful. For instance, if his clones could multiply infinitely and each had the power of the original, that would be a huge advantage.
One thing could be unique chakra abilities. If in a fanfic, Naruto discovers a new form of chakra that gives him unlimited power, he could be stronger. For example, a chakra that can nullify all energy - based attacks like Goku's ki blasts.
In my opinion, it's highly unlikely. Goku has mastered multiple forms and techniques that give him a wide range of powers. Saitama's one-punch style might not be effective against Goku's diverse skills and battle experience.
In general, it's a bit of a toss-up. The strength of Manga Goku and Anime Goku can vary depending on the specific arcs and battles. Sometimes, it might seem like one is stronger in a particular situation, but that could change in another.