"Who's a better player between LeBron James and Michael Jordan? I would say LeBron James," Mayweather said on "The Waddle & Silvy Show" on ESPN Chicago 1000. "And I'm from the Michael Jordan era. I'm 36 years old."
Mayweather, who's a huge NBA fan, was in Chicago with Canelo Alvarez to promote their Sept. 14 fight in Las Vegas. Thousands crowded into the Chicago Theatre for the event.
"We're not talking about championships, because if we're talking about championships, Bill Russell has 11," Mayweather said. "And the dunks Michael Jordan was doing in the dunk contest, Julius Erving was doing it. ... Really when we're talking about who's the best basketball player, it's just an opinion.
"Do I love Michael Jordan? Absolutely. He's an unbelievable player. He was the best in his era. But in this era, it's more than just one. It's an argument. You've got Kevin Durant, who some days I feel he's better than LeBron."
Mayweather wouldn't confirm reports that he bet $5.9 million on James and the Heat beating the San Antonio Spurs in Game 7 of the NBA Finals.
"I'm not here to talk about gambling," he said with a smile. "I like to gamble. I'm not here to talk about gambling. Let's talk about basketball. Let's talk about football. I'm a sports fanatic. I like to bet. Let's just say I like to bet."
But he wasn't shy talking about his admiration of James and the Heat, who have won back-to-back titles.
"LeBron James I'm proud of you, also," he said. "I never turned my back on LeBron James when everybody said it wasn't right for him to go to the Heat. He went there and did what he said he was going to do."