What is your main the best at?

Like the title says. I was watching a video on how it's difficult to make good tier lists for this game because of how technical and variable every individual match is. There are so many situations that can happen in a match, which leads me to wonder if there's a character who isn't the best at ANYTHING. So, restating the question, in what situation is it most advantageous to be playing your main as opposed to any other character?