well, it wasn't so much that superman
couldn't properly 'beat' him. it's that he
wouldn't. it would be effortless for him to shoot some heat vision straight into lex's brain and be done with it but that would have a terrible effect on sales.
here's what i'm thinking: luthor obviously has a lot of political strings at his disposal. after all, he was president. i know you don't care about that but that put him in a position to do a lot of things he had always wanted to. but for fisk, controlling HYDRA and the other factions he's affiliated himself with would also afford him a lot of power in dark places. fisk has enforcers like tombstone and, uh, the enforcers, but luthor has people on the payroll too, so they're not going to be able to cripple each other with capes or hired powers.
i think, at the base of it, it will come down to this:
this suit. this suit right here. lex slips that baby on and knocks fisk onto his back, you can bet that is going to look like a big turtle trying to flip itself off its shell.
ftw: lex luthor