I think Kabuto already surpassed Oro, but that's just me, if anyone likes to prove me wrong please do it in a proper manner
So for the Thread : Kabuto Got this one.
ok since no one else is going to do it, I guess I am gonna have to at least give it try.
The sage training of kabuto requires special kind of body. Kabuto managed to create that body by absorbing the power of Orochimaru. So even though he was imperfect as a sage, Oro is the ultimate source of sm kabutos power. Much like how shodaime was the source of yamato's woodstyle. So technically Oro>kabuto just like Shodaime>yamato.
I dont know it just hard to count Orochimaru out. I used to think part of him was able to escape totsuka and then somehow merged with kabuto.
p.s I might be a little biased cause I find it hard to put a jobber(former) like kabuto getting over orochimaru(former boss). Kabuto is skilled, intelligent and well informed. But I think Oro was always on top of him in each of those categories.