I'd pick someone like KJ Noons over Conor in a boxing match, but Conor would smoke him in an MMA match.
I don't think people really realize that Conor doesn't even remotely fight like a boxer, nor have the training in it. He's pretty much an amalgamation of karate, kickboxing, and muay thai.
That's not a knock on Conor. Roger Gracie would be absolutely murdered in Olympic judo despite being the most accomplished BJJ practitioner in the history of the sport. Shits different.