Andy Cohen Thinks Michael Strahan Will Regret Leaving Kelly Ripa

Michael Strahan just made the biggest mistake of his career by choosing 'GMA' over "Live! with Kelly and Michael" ... at least according to Andy Cohen.

Andy took a stand for his BFF, Kelly Ripa, during his SiriusXM show Monday morning ... calling out Strahan for taking the 'GMA' gig. The way Andy sees it, it's a numbers game and Strahan's taking a big risk leaving his established spot on 'Live.'

He said, "What happens if the ['GMA'] ratings don't go up? What is going to happen to this sweet man? By then she will have a new co-host."

Andy's already said he doesn't have time to take the job with Kelly -- if it were offered to him -- but he does have another good friend in mind for the job.