How much are you planning on wagering? At -300 it just doesn't seem worth it to bet on Conor. I do think Conor has the edge, but Cowboy's been in there with everyone and beat a lot of very good fighters, and has a distinct grappling advantage along with being the bigger fighter. Always a threat to take anyone out with a head kick too. The odds should be a lot closer than they are IMO, so I don't see any value in betting on Conor.
However if you're convinced the fight is fixed, go ahead and bet your life savings on the man.