For decades by far the most argued question in the comic-book world is:
Who will win? Batman or Superman?
The answer is... BATMAN.
Now the simple answer to that question would be, BECAUSE HE'S THE FLIPIN' BATMAN. But, once you go into more detail, you find there's a lot to it.
1. He's done it multiple times
That's right kids Batman (or his plans) have killed (or defeated) the justice league, INCLUDING SUPERMAN.
The proof you ask?
- The Justice League DOOM storyline,
- Batman Endgame part 1
- The Dark Knight Returns
- Batman: Hush
2. Batman is PRACTICALLY made of Kryptonite
In the Hush story line he had a kryptonite ring, he even has a kryptonite suit.