But Papist, Batman has like 100 times more character development than Supe.
If you mean TKD vs. Man of Steel, then I would agree. There are some script and plot problems with Man of Steel that prevent the entertaining moving from becoming a great movie.
If you mean Supes vs. Batman in general, then I disagree. In reality, the reason that I think most side with batman is that it is sort of "cool" to do so. As Fabio has pointed out on another thread, in our society, we tend to glorify what is dark, broken, and disordered. Probably because it provides us with goals that we can all easily reach without much work. It's easy to like Iron Man and Batman because they teach us that we can be great without actually being good. Very lazy stuff.
However, when societies tend to put greater value on manly virtue, they create heroes and ideals that are impossible to reach. Yet, there is something good in this, because it makes us strive for something, for goodness. In the striving, and even the failing, we become better people.
Now back to Superman's development as a character. I think people fail to recognize the deep conflicts which Superman must face, conflicts that shapes who he is. Superman can never do enough. It does not matter how powerful, or how good he is, he can never save everyone, and he can't end all suffering. He may wish he could, but he cannot be in all places at one time. In choosing to save Alice from falling off a building, he may have failed to notice an entire school burning down, with children inside. The enormous weight of responsibility is simply beyond bearing.
And beyond that, it would be inappropriate for him to right all of our wrongs. If he tried to, we would not grow as a species, and would become ever more dependent on him. Thus, there are some problems he has to let us sort out ourselves. For example, he just can't fight our wars for us. He has to remain apolitical.
Reading the Death and Return of Superman series in middle school shaped my understanding of the Man of Steel, and I think he's a much deeper character than those who are "cool" and "with it" would like to admit.