..........
Rinnegan Obito obviously wins. Bijuu Sealing Chains bind Kurama, the 6 Bijuu nuke it to death with repeated Combined Bijuu Dama, and Obito beats his kid self.
I can't properly remember that fight with the Bijuu but can Obito use Bijuu and Gedo Mazo at the same time? And can 6 Bijuu take care of Kurama when half Kurama was stalemating them?
Btw this is not Kid Obito. Kid Obito doesn't have Izanagi. This is Akatsuki one with the Zetsu suit. Sorry for the misunderstanding.
Btw 1MS Obito still has Izanagi to catch Rinnegan Obito off guard