Very rarely is this won by a GC guy (only Froome in the last decade) and the number of stages that look breakaway suitable mean this trend will likely continue. So I would tentatively rule out Bernal, Yates, Evenepoel etc. Of course, if they were to fall out of GC contention but remain healthy they they would have a huge chance.
De Gendt, Bouchard and Guerreiro are all proven KOTM winners but I am not sure any of them are at their top level.
So I come back to Mader, who was supreme today. To ride away from Mollema and hold off a pretty intense chase was outstanding. He has the power to get into more breaks and has a decent sprint if he finds himself having to contest mountains points. I'm not too worried about him being able to hold his form, either, remembering that he got stronger as the race went along in last year's Vuelta (his first Grand Tour). He might be the $5 favourite but I think that is actually good value.
I would also love to see Pozzovivo have a concerted effort at it now that his slight hopes of a good GC result are gone.