He was by far the best driver in the world and it showed. Very few drivers could match his car setup skills or awesome driving skills.
How do we know he was the best driver in the World? He never competed against the likes of Gil De Ferran, Jeff Gordon, Sam Hornish. He was the best of his era in F1 that is all. He to classed as the best in the world of his era he needed to have raced against other champions and all types of paved circuits.