Without using "Gods", it's Superman.

Why? Because there is no real limit to his strength. It's been proven time and again, that Superman is as strong as he needs to be. Batman has Kryptonite? Cool, throw spiderman at Batman, and Batman gets owned, because he isn't prepared to counter someone as smart as he is, who ALSO has superpowers that Spiderman has.

Secondly, Goku will get owned by Superman, as evidenced:
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