Hashirama. Muu's only chance is hitting his chest and head with a Dust Release.. but literally everybody knows about Muu's main abilities and Madara wiped him out pretty easy. Hashirama would do worse to him.
Madara curbstomped Muu and Ohnoki at the same time. Hashirama is even stronger than him. Dust release is powerful but nowhere as powerful as a Kyuubi Bijuudama and even that couldn't slowdown Hashirama one bit. Muu has no chance.
Dust Release is definitely more powerful than a Bijuu bomb, it would easily eat right through one. The problem for dust release users is just about everybody knows about dust release and how it works therefor making it extremely unlikely to land it on an opponent who knows all about it. If he lands one Dust Release on Hashirama's head and chest then he wins no doubt but that will be extremely unlikely.
Dust Release is definitely more powerful than a Bijuu bomb, it would easily eat right through one.
I meant in terms of sheer destructive power. Dust release is a focused attack while Bijuudama is chaotic and just about destroys everything in it's vicinity. Hashirama is just way too strong, almost unfairly so. Muu can make himself invisible and try for a sneak attack with the dust release but he has a limit to the number of times he can use it. That's just about the only way he even has any sort of chance in the battle.
How can hashirama track muu ? If he become invisible and cuts off his chakra then hashirama can't sense him. Any constructs of hashirama can be taken out with ease by muu. I'm not saying muu wins, but hashirama can't just stomp muu .
Senjutsu. Hashirama is a perfect sage. A tiny bit of senjutsu chakra from Edo Hashirama allowed a blind Madara to sense and react to Tobirama's Hiraishin. Now apply the same logic here, alive Hashirama is stronger than his Edo counterpart and his senjutsu that much stronger. Muu is nowhere near as fast as Hiraishin. True he can erase himself and run away but that would defeat the purpose of this debate. The moment Muu tries an attack, he uses chakra and will be found out by Hashirama. Senjutsu allows much faster reaction time and can sense over a wider range and it's not as if Hashirama needs a lot of time to infuse senjutsu chakra. He could do that almost in an instant. Frontal or Sneak attacks, Muu has no chance.