I was never high on Golota. Mercer at his best was an animal. I think Kabayel beats Golota but I'm taking Mercer over him.
Kabayel has already demonstrated that he's an extremely tough guy with solid fundamentals who doesn't need a "best night" to elevate his standing. He'd break down Golota after a rough two or three rounds and make Mercer quietly quit by unanimous decision and excuse.
I'm confident he'd beat Golota. Mercer? He blew so hot and cold it really depends which version of him we'd be getting. At his best I'd take Mercer, on an off night Kabayel beats him.