MMA Legend Bas Rutten: Conor McGregor Should Box Next, Here's Why

Here's something you don't hear everyday -- a UFC Hall of Famer saying Conor McGregor's next fight should be in BOXING, not MMA!

"If he's a smart guy he should keep on boxing -- that's what I would do," Bas Rutten told TMZ Sports.

Don't get it twisted -- Bas says he wants to see Conor come back and defend his UFC lightweight belt ... but at the same time, thinks it'd be crazy for McGregor to leave Manny Pacquiao/Floyd Mayweather money on the table.

FYI, McGregor told us he wants an MMA fight next ... but would he really turn down another HUGE payday??