Obito wins this pretty easily.
Orochimaru can't only be beat with Genjutsu, he may be strong but he's not invincible.
And he hasn't even shown a great many techniques, certainly not many destructive ones.
Obito can take hit's off current Naruto and still live, and he heals.
Orochimaru has no real way to hurt Obito, even if he summoned the Hokage they still can't hurt him his jutsu is absolute and his teleportation rivals Minato's.
Oro's only chance would be to use Dragon Sage Mode but he can't and even if he could it wouldn't grant him an instant win.