Gennedy Golovkin vs Nigel Benn Prime vs Prime 15 Round Fight who wins?

I say GGG beats and TKO's Nigel Benn.

GGG will immediately know how dangerous and unpredictable Benn is and immediately set him up behind that power jab. GGG has Light Heavyweight / Cruiserweight type power, is extremely precise in punch placement and footwork, and can alter his strategic output. Nigel Benn's only chance would be in the 1st 3 rounds - where a well placed punch could stun GGG (something that's never been seen before). But I highly doubt that happens.

The problem here would be that Nigel Benn's style is kind of like a 'cousin' to GGG's style. They both are pressure fighters, but Benn's style is more predicated on swarming and using athletic explosiveness (leaving behind a lot of defensive liabilities). GGG likes to crowd (taking away your space and timing) from mid-range, and will set you up for counter traps. If GGG observes that a fighter isn't falling for his mid-range traps, then he will resort to a simple 1-2 base (sometimes throwing many 1's in a row, sometimes throwing a lead 2). His jab is a powerful jab that hurts. He eventually breaks down fighters enough by the mid rounds before resorting back to his mid-range strategy.

Nigel Benn was great, but compared to other all time great swarmers like Jake LaMotta, Mickey Walker, Carmen Basilio, Joe Frazier, Emile Griffith - Benn got hit way too clean, was more susceptible to stunning, and could be sporadic at times. The guys I mentioned were more relentless, rolled away from & weaved under punches more, and had a more defined strategy for their swarming tactics.

Nigel Benn by KO in round 13.

Benn

Benn

Golovkin beats him.

I'll go for ggg