10 tails would win IMO
Lol what is this? The ten tails stomps.
Madara + Kurama were putting up a good fight against Hashirama's best. A weakened Kurama, the Hachibi and the whole allied shinobi nation were having trouble with the weakened Juubi we are seeing in the manga, and it has been assumed that it hasn't even shown it's full strength yet.
Hashirama might be able to subdue it for a bit and keep it occupied, but he definitely isn't winning, and that's for the Juubi we're seeing atm in the manga. Hashirama wouldn't even be a challenge for a fully-powered Juubi.