I think Superman Returns had huge potential and the scene where he is flying and using heat vision to melt the glass and protect people is just PERFECT superman and creative outside the box thinking about Superman's powers. I think Man of Steel had someone what good fight scenes, but in the end it was Superman just using brute force. I really want to see Superman be creative and smart with his powers. Using all of them for outthink, and maneuver his opponents. But very few movies show that side of Superman. He should be having fun showing the futility of the bad guys evil actions to them. That is an important trait of Superman's.
Batman also has a style of fighting. It is misdirection that leads to fear and mistakes. Batman toys with enemy is a very brutal way, picking his targets eliminating them from biggest treat to weakest, and uses the weakest to get information...But it isn't about showing futility and invulnerability...but about causing as much fear as possible.
The Flash is the community hero. He is about building a better community and that includes trying to reason with his villains and form relationship with them. He understands above anyone else that these are humans and people and if you can reach them they can be saved from their life of crime. Superman has that hope too, but he tends to be more global.
Wonder Woman is the warrior. Get the job done with as few casualties as possible, but she is like Batman and will give no quarter. But she is also an ambassador which means she struggles with how she would like to handle the situation and how she should handle it.
If you can't get these 4 characters right, you can NEVER get Justice League right.