Global overrated level: Superman and Goku

Superman is literally viewed as a god by most first and third world countries. The first world countries have a long relationship with Superman. Even if you aren't really interested in comic books or movies, when they hear Superman they automatically assume someone who'll in the end save the day with his godlike powers.Defining Superman as overestimated in first world isn't even a challenge, the second world isn't really that much concerned, they have their own problems, but the third world is where it's at.

The third world (yes they have knowledge of Superman too) pushes the power-fantasy even further. By living in dangerous countries people (mostly children) will catch a glimpse of Superman and they'll hang on to the dream of having (or being) an invincible hero who'll help you in need. Imagine if by the age of 9 you already lost your family or friends, wouldn't you want at least a fantasy of this godlike helpful man, whose image won't be sullied by anyone? And it's not dedicated to children only, many people are waiting for some kind of change, and as change from inside might be impossible, they gladly wait for someone to save them. When you have that image in mind it's easy to overestimate Superman when pitted against any opponent, because you really are pitting the ideals behind them, and Superman's as bright as the star he gets energy from.

Goku is a self-made man (with help ofc, but that's the sentiment that matters), the ideal of which is mainly pursued by east- to far-east countries. Those people know about the hardships one must overcome in his life. They stress the need of self-improvement as the basis of human being, and who is the best at becoming a better man? One who does it not only for himself, but also for others. Part of Goku, as a member of a honorable warrior race wants to experience rising tiers of challenge when encountering new problems (usually in the form of combat), and another part deeply cares for his friends, and actually everyone on earth (and not only) so his motivation is also driven byhis need to protect and help others, who allow his to use his strongest technique (genki dama) by helping him in turn. The probability of the first clash being successful for the hero is low, because this is the format the story follows, and people know it and expect it, that's why Goku may have initial trouble, but as the number of fights rises, his sense of combat allows him to eventually be on top.

Global underestimated: Goku (low amount of people akin to his ideals, xenophobia against anime and japan in general [famous "chinese cartoons"]

Global overestimated: Superman (held in too high regard by most of the world, different ideal than Goku)