In all fairness, Marquez had already seen his best years (physically) by the time he started fighting at 140. That considered, I don't think you are going to hit Marquez with a whole bunch of right hand punches because he is smart and smart guys don't get hit with right hands. Tszyu used to get hit with them, but then he got smart and turned his body.
I think Marquez is more mobile, and I think he is smarter. I think that Tszyu has the better right hand, Marquez the better left. I think that Marquez would win, and I feel pretty good about that, though it wouldn't suprise me to see it go the other way.