I'm glad to see someone who agrees with me about Superman.

I'd love to see him show that his spirit isn't being broken, no matter how much hate the world throws at him, no matter how conflicted he may feel. In BvS he seemed close to giving up completely. And even though he kept saving people, I never got that warm feeling that I should get from Superman, whether he is conflicted or not.
Speaking of Hulk, I actually cheered for him in Avengers when he was saving the day. I, and so many other people, fell in love with the Hulk in that movie. I want crowd-pleasing stand up and cheer moment for Superman in Justice League, like Hulk got in that movie. The tone doesn't have to change at all to give the audience a moment of pure joy like that. Dark tone doesn't mean it has to be joyless.