Oscar De La Hoya -- Jay Z Is Great For Boxing ... Better Than Mayweather

Sure, he wants to take him for $100,000 ... but Oscar De La Hoya says Jay Z is GREAT for the sport of boxing ... unlike Floyd Mayweather.

The Golden Boy just ripped Floyd in a "farewell letter" in Playboy ... claiming the sport will be BETTER without him in it.

But when we saw Oscar at LAX moments ago, he had a completely different opinion about Jay Z -- who's been loading up his Roc Nation Sports roster with big name boxers.

"He's great," Oscar said of Jay Z ... "He's a breath of fresh air."

Oscar and Jay also have a $100k bet (for charity) on the Canelo Alvarez vs. Miguel Cotto fight -- since Oscar reps Canelo and Jay reps Cotto.