Well, it would be hyperstorm IMO.
Hyperstorm possesses virtually infinite psionic power which he can draw endlessly from
hyperspace, from which (in the
Marvel Universe) the primordial energies creating the
fundamental forces of the
universe,
strong nuclear force,
electromagnetism, the
weak nuclear force and
gravity flow into our plane of reality. Controlling the four fundamental forces should theoretically allow him to restructure, create or destroy matter at will down to subatomic level, as well as creating electromagnetic fields and electrical currents, making matter
radioactive, manipulating gravity, causing nuclear detonations, emit enormous energy blasts, use his psionic powers to increase his physical strength and generally accomplishing nearly anything he sets his mind to. He has also displayed
telepathic abilities, both as Hyperstorm (
Fantastic Four Unlimited #12) and as his otherworld counterpart David Richards (
Exiles #59). For the latter, his powers has been described as an amalgam of the powers of
Professor X,
Magneto and the
Phoenix Force. He can also teleport through hyperspace from one place in the universe to another, possibly at immeasurable distances. He has been seen to counter the
Invisible Woman's forcefield with one of his own making, unsurprisingly since she draws her power from one of the higher planes of hyperspace, though highly limited compared to Hyperstorm's own hyperpowers. He is also
telekinetic, considering the fact that both his parents, as well as his grandmother
Jean Grey, had telekinetic powers. His power level has generally been compared to that of
cosmic beings rather than that of other very powerful
mutants such as
Franklin Richards or
Nate Grey. Hyperstorm may be the most powerful mutant witnessed to date.