I think it depends on the purpose of the heroes:
Goku was created as a classic fighter who is training each time to fight stronger and better opponents, to break through his limits.
Superman was created as an representation of an Ideal, a God that us mortals can look up too. A God does not have limits.
Goku seems to have weaknesses but then surpasses them, eventually, with time and training.
Superman, in the comics...and movies, has ONLY ONE weakness. Meanwhile his powers are, seemingly limitless. He is the Ideal Hero, the Pinnacle of Heroics. Goku will never use that one weakness Superman has, which makes Superman...well limitless.
What happens when someone who can break any limit (Goku) faces off against someone with no limits (Superman)? I gotta give it to Supes.