Kante won the league with unfashionable Leicester, then the league again with Chelsea, the champions league and a world cup. Great player but not the best ever because team achievements don't define an individual.
The World Cup is knockout football. You don't have to be the best to win.
Maradona was before my time so I'm relying on video. He was clearly incredibly talented but he was lucky to be playing in an era where footballers weren't always professional. His lifestyle could cope playing against drunks. He wouldn't last long at the top three days with his lifestyle against the athletes of today. Tactics have changed and everyone is much more disciplined. Messi has been the best player, playing against tougher opponents for longer.
1 knockout cup final will not define his career. He is the best player of all time whether his team wins or loses. Would be nice to see him score the winner just to remove the argument but it really is irrelevant. This is his 2nd final and will probably his 2nd World Cup Golden Ball. That's impressive even if he doesn't actually get his hands on the trophy.