At most Superman is only a 3-A universe level Goku in his base form is multiple universes. There is a clear difference in their power. Goku speed reaches flash, go easily contented with most versions of Kal-El
My take. Superman is an idiot. Lex and Batman outsmarted him and beat him to death. He is not superman outside of the earth, that has a red star/sun. While Goku can still maintain and can increase in power, skill and strength wherever planet he goes. And he is smart and great martial artist. Goku could just use his teleport and bring supes to other galaxies that has red sun.
At most Superman is only a 3-A universe level Goku in his base form is multiple universes. There is a clear difference in their power. Goku speed reaches flash, go easily contented with most versions of Kal-El
The only ones Goku can’t contend with are end of time thought robot a.k.a. cosmic armor, Superman, and maybe a few others
My take. Superman is an idiot. Lex and Batman outsmarted him and beat him to death. He is not superman outside of the earth, that has a red star/sun. While Goku can still maintain and can increase in power, skill and strength wherever planet he goes. And he is smart and great martial artist. Goku could just use his teleport and bring supes to other galaxies that has red sun.