Hmm...
I think Alekhine. His games have a higher percentage of wins than those of any other World Champion, and his drawn games are on average among the longest of all champions. Alexander Alexandrovich is the only WC, who died with the title and as Kasparov said: "Alexander Alekhine is the first luminary among the others who are still having the greatest influence on me. I like his universality, his approach to the game, his chess ideas. I am sure that the future belongs to Alekhine chess."

Who do you think in chess history was or is the best?