My gut tells me Tobirama but I don’t really remember Naruto like that, I do remember that Minato used the same technique that Tobirama uses on Ay and Ay got blitzed iirc. I think from there Tobirama would take it, plus he’s pretty versatile from what I remember.
There's no contest
Tobirama is faster
has faster reactions (guy managed to dodge Juubito attacks - that feat instantly puts him far beyond the 5 kage of Ays generation)
he also has more chakra density and power - he can destroy his surroundings just by raising it - Ay has to transform its nature before he can accomplish this feat
This means Tobirama is more durable and less exhaustible
Plus he is stronger than the trollkage who made Gaara and Ohnoki look weak, reputed as the strongest Suiton user ever, and Ohnoki in the eyes of many was at least on par with Ay
He has Edo Tensei
He has infinite exploding tags like Konan did
Tobirama also oneshot Izuna when he had the mangekyo Sharingan. When Sasuke had the Mangekyo he put up a fight to Ay and managed to have one of Ays limbs amputated
It's a totally different scale
Somehow we've seen some mad Kisame wank here, but it's irrelevant. I dont understand the logic of the guys trying to say Ay beats Tobirama