Probably the kages cause there still 5 rather than three.
Defiantly the kages they got gaara for defence, oonki for his powerful particle style, A for speed and strength and mei for different nature types to counter.
I think the kages are more diverse which may help the situation better.
The sannin I think if orochimaru can use edo tensei.
Yes, Prime Orochimaru.
Yes, Prime Orochimaru.
Definitely the sannin then, Orochimaru Prime with edo tensei, jiraya SM and Tsunade with her regenerating abilities, medical jutsu and super strength is too much for the kages to handle IMO and would give madara a harder time, they MIGHT be able to defeat him.