I'll go the other way...for now. But check with me this time next year. Also I think Azumah was a genuine superfeather....isn't Floyd well past that size at this point? So I have to go pound for pound in this one.
Nelson would take this IMO. He had great stamina over 15 and I can see him taking it to Floyd and beating him. At his very best Nelson could cut the distance between him and his opponent in a fraction of a second. He was also a damaging puncher and worked the body well.