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Finally we agree on something.
Yeah, I also think that Norman's madness gives him an advantage here. And yes, Hobby thought he was stronger at first, but now?
Physically they're evenly matched, even though I would go with Norman Osborn in a fight to death. They both have the same powers, but Kingsleys version of the Goblin serum didn't have the side-effect of insanity. But it is that insanity that would probably give Osborn the edge.
They fought briefly in SPECTACULAR SPIDER-MAN #261. Kingsley was chocking Osborn, who then stated that they're evenly matched. They continued to trade shots, until Spider-Man knocked them both down. Spider-Man went on to save civilians, while both Goblins fled.