Probably Madara high diff. He still has his MS. Tsunade would eventually run out of chakra.
On the other hand Madara's genjutsu is useless in this situation, since it's not tsukuyomi. Katsuyu can easily dispel normal genjutsus. Tsunade could fight equally with five susanoo of that size which actually tried to kill her but COULDN'T. I believe Madara would be a lot more cautious in this kind of fight.
It could go either way, since Tsunade's byakugo ability is really good against him. AND now she can just worry about her self and forget healing and giving other people chakra.
I honestly believe it could go either way. Weird. That is if she survives a huge katon. I bet if she hides in Katsuyu she could. I mean, she could even hide in the HUUUUUGE Katsuyu and nothing could touch her.