The Death Star is the most powerful battle station ever constructed. And it's virtually indestructible — once you take care of that one tiny reactor vent thingie, that is. But meanwhile, Superman is also impervious to most weapons, has insane super-strength and can travel at Mach Infinity. And he's already polished off Warworld a couple times.
So if it came to a smackdown between Superman and the Death Star, who would win? You decide!