Hashirama > Obito
Hashirama < Obito with 10 tails power
Everyone should know that with the 10 tails power, you can PWN nearly anyone. But don't forget that the Hokages have not been ressurected (via IWR) in a full powered state, they have been brought back being 'nearly at full power'. Hashirama and the kages were able to restrain the 10 tails in its 3rd incomplete form despite only being in a nearly full powered state and counter its attacks, this alone says alot about the Hokage's powers.
The being that attacked the shodai and Nidaime hokage was the 10 tails in control of obitos body, basically the 10 tails in human form, not obito to say therefore that hashirama is weaker than obito is an misjudgement of what hashirama meant when he said 'this man is stronger than me'. He really meant that when he gained the 10 tails power by being its jinchurikki, he became stronger that he was, partly due to hashirama himself only being in a 'nearly full power' state.
Obito is currently not in control of his mind or his body as his response to minato clearly shows. It is rather the 10 tails having gained a vessel, a mind so to speak, of which has enabled him to focus his attacks more as demonstrated by his attack on Hashirama and Tobirama. Don't misunderstand obito is immensely powerful, but is nowhere near Hashi and Tobiramas level of power, but now that he gained the 10 tails power (and also ,which was mentioned by naruto, has in turn gained chakra from the other tailed beasts in addition) he has gained an advantage over the two.
Also, to those who state 'Juubito' > SO6P....are you serious.
The SO6P even without the 10 tails would beat juubito, he beat the 10 tails in its perfect final form, became its jinchurikki having FULL control, scattered its power across the worlds surface on his death bed and encaged the 10 tails body via chibaku tensei creating the moon, the latter two he did on HIS DEATHBED using HIS OWN POWER.
SO6P > juubito anyday, that is obvious to the mind.