It's not just the box office collection, Cameron's passion for filmmaking is quite evident from the fact that he takes decades to make a movie, to develop the technology necessary for making a movie as immersive as Avatar.

And his older films like Titanic, Terminator 2, Aliens, The Abyss are more than enough to put him among the greatest filmmakers who have ever lived.

But if you're under the pretext that James Cameron has made only one movie in his career, i.e, Piranha II: The Spawning, then yeah, Michael Bay is obviously the better director.