In the 35 years I've been watching basketball, I've never seen a putative superstar who flat-out wet the bed in big situations like Karl Malone. He didn't want any part of it. It wasn't just that he had the bad luck to go up against Jordan; he didn't want the ball. All the stuff they said about LeBron until this year was true of Malone his whole career. There was one year when Bill Walton, announcing the finals on TV, basically ridiculed Malone for disappearing. "Where is Karl Malone? Where is Karl Malone?"
Duncan won multiple titles, played like a lion the whole time, and morphed into whatever kind of big man his team needed depending on what Popovich wanted to do. Duncan was better and it's not close.