I'd actually say Hashirama since Juubito is mentally challenged in his First Form.
Obito is a Retard in his V1 State
He's also immortal and nearly invincible.
-Hashirama's techniques get demolished like his God Gates and Hokage barrier.
-He admits inferiority to Obito.
-He got blitzed alongside Tobirama.
Get acquainted with the VS section. Both your scenarios aren't allowed.Hashi's got no way of putting Obito down, and since this is Obito jsut after becoming JJ, he's either going to take controll of the Juubi, and proceed to rape Hashirama, or fully loose control and turn into Kaguya, who rapes Hashirama anyway.
Juubito med difficulty.
If he can managed to get chakra arms around the barrier that could fit the Juubi plus it's tails it can easily get those same hands around SS then proceed to rip it apart. Not to mention Hashirama has no way of putting Juubito down; his strongest methods of restraining (Hotei gates) were shattered easily.
He couldn't even do that to Minato and Naruto's Kurama Avatar before they slapped his arms away with their own tails let alone SS, which is FAR stronger when it comes to physical power, and has many many more hands, so your logic is terrible. Chakra arms get slapped away like they did by two weaker constructs, and SS turns him to paste. Why would he have to restrain Juubito when he can outright kill him? He can't negate Senjutsu, nor does he even have Onmyoton, and he can't tank Shinsuusenju's punches, and he's not immortal. He dies.
Hashirama would not have the time to summon SS bro