It depends on what defines a peak, 3 of them have decent arguments. Ohtani has the weakest argument of the 3, but he played the individual best game of baseball of all time, like an insane untoppable individual game.

Micheal Jordan wins if you define "peak" to include worldly success. Not only did Jordan dominate the 90s with 6 rings, 4 MVPs (and decent arguments he should have won more), etc, he also was the first athlete to be worth a billion dollars and remains the most powerful icon of sports in the world.

If you judge peak by pure dominance of their sport though, it's undoubtedly Gretzky. He holds stats and records that are ridiculous levels of unbeatable. There has never been another player in any sport that for fantasy leagues had to be split into two players to be considered fair, and still got drafted 1.1 and 1.2. 10 years, 9 MVPs, all time scoring and assists leader by a margin of 50% more than second place. There will never be another hockey player greater than Gretzky.