Definitely KO's Cotto and Lee... Canelo hasn't been stopped yet but I think GGG could be the first to do it.
I agree 100%. I'd add everyone on MW to the list, including Quillin and Jacobs. I've seen all those other MW's get hurt by guys who had nowhere near the skillset or power that Gennady has. It seems like you'd have to be a very technical fighter with good speed and foot movement just to be able to last the full 12 with him.
I could see James degale going the distance and stinking the place out. Middle? Not anyone off the top of my head. Canelo maybe
Lee uses his height advantage to keep GGG at range, GGG gets frustrated and starts forcing the issue too much and gets KO'd by Andy circa 5-8.