The most important decision you can make as a showrunner when you're doing a pilot is who's in it and who's directing it.
You have to always try to think about them like real people first, and not just heroes. They have to be real characters. As people do more and more superhero stuff, the characters are what distinguish it, just like in cop shows.
There were moments where Supergirl gets a thrashing in the pilot, where if a man in the 'Flash' or 'Arrow' pilot got beat up, people didn't visibly wince. And I watched in testing, people in the audience really became uncomfortable by the fisticuffs and the action. But then, they were elated and cheering at the end.
I was a DC fan; The Flash was always my favorite character. He was sort of the most average guy amongst all of these icons, even though he had super speed, you know?