I would go with Hashirama FTW or "Draw." Why?
Why would Harshima win the battle?
His hype lately, do to his Mokuton Creation, has become something compared to the hype of the Sage, which Kabuto stated "It was said to be fairy-tells." IDK, looking at the power handed to Madara by Kabuto, which is a fragment of Hashirama's power, would seem to me that Hashirama's Mokuton Creation is Superior to that of Rinnegan.
We also have to look at the current descriptions and abilities of Hashirama by looking at features such as his age, which in the Manga, always depict him in his "Prime." Your "Prime" is were your mostly at the peak of your abilities and near the beginning of your downfall. His abilities tell the tales of his greatness that which would seem be on par with the Sage.
Why would the battle end in a draw?
Both Nagato and Hashirama are consider legends based off their respective Kekkei Genkai abilities; Nagato with his Uzumaki Traits and Rinnegan, and Hashirama with his Mokuton Creation. These abilities far extend the power of normal Ninja. Both ninja have the power to counter each other attacks and abilities through attacks and defense of their Kekkei Genkai. If this continue to happen, a stalemate, then one who falls first would apply to the bout. However, both stamina are similar being that Uzumaki is a distant cousin.
The battle can't be determine by simple attacks and dodges of certain maneuvers and Jutsu excution, but it can only be determine who can last longer in the battle. These method can't be put into placed because of their respective DNA or Kekkei Genkai. Thos, leaving the match in a draw.
