This week I would like to compare two more primary characters of the Marvel and DC universes, the redoubtable Professor Charles Xavier and the inimitable J'onn J'onzz. Both are considered among the greatest telepaths in their respective universes.
J'onn first appeared in 1955. He is an advanced telepath, able to connect with the entire planet at one time in order to locate someone. He is also an advanced shapeshifter, capable of changing his size and shape to anything he wishes. His density can be modified at will; he can phase in and out or become incredibly dense. He can use energy attacks, fly, turn invisible, has x-Ray vision, can create force fields, and has strength, durability, and endurance to match Superman. He was at one point weakened by fire, but now only certain types of psychic fires have any impact on him.
Professor X first appeared in 1963. He is also an advanced telepath and one of the most powerful on Earth. However, apart from telepathy his abilities are nothing like J'onn's; unaided he can only contact minds within a 250-mile radius. He can go much further than that, touching every mind on the planet, but he must use his artificial creation, Cerebro, to do so.
His telepathy has led to other powers. He is able to learn and teach instantly by touching another person's mind. He is able to create psychic bursts, induce paralysis, create illusions, and project himself astrally. However, the professor only has his mind. He cannot stand because he is a paraplegic. His strength, durability, and endurance are also less than ordinary because he cannot exercise like a normal person. He cannot fly or use any form of telekinesis (movies notwithstanding). His senses are ordinary.
As with Wally, J'onn's powers are so far beyond human it is difficult to imagine a worthy adversary for him. He also has no personality wrinkles. J'onn is either separated from his people or the last of his kind (depending on the era his story is told in), but no attempt has ever been made to explore that aspect of his personality. He is another flat character from the DC pantheon of pseudo-gods.
Professor X is powerful, and even more so with the support of his X-Men. But he is not all-powerful. He is vulnerable to the most basic attacks; his wheelchair can be tipped over to leave him prone. He cannot outfight someone with even a minimal knowledge of streetfighting, either. His crippled state works perfectly for a character whose goal is to peacefully champion mutant rights. It makes him interesting, too. It just doesn't make him a superhuman hero.
So does his humanity. Xavier's human mistake of women-chasing in front of his ward allows him to lose Mystique in the fourth X-Men movie. His ability to empathize with Magneto makes the pair one of the most interesting adversaries in all of comics. His depression almost loses him the future in Days of Future Past. Professor X is one of the most powerful of the primary Marvel characters, but he is no match for his counterpart in the Justice League in combat, just as J'onn is no match for Professor in how interesting the two are.