Back to the subject.
Comparing someone's abilities with some others in a given art form is valid up to a certain point.
Past that level of skill, the person has achieved "mastery", some are called "geniuses", and debate over who's better becomes irrelevant.
Mozart or Beethoven ?
Van Gogh or Rembrandt ?
Pacino or de Niro ? (or Seagal ?)
One can have preferences, but objective criteria don't apply anymore. That's the way I feel about O Sensei.