I think the men are the strongest. It should be Taylor and Elliot. Chris proved last night that he has no control over his voice. He is limited in his musicianship (mainly by his screaming.) If he knew how to control his voice properly, he wouldn't have been cracking all over the place.
He said all the singing was taking its toll...but everyone else is singing that much as well! It's all the singing improperly, ie. screaming, that is taking its toll on Chris.