From what I've learned from both characters, Aizen would be the victor of a battle between the two. I don't think other characters should be used in battles against The Sage Of The Six Paths, we haven't seen him in battle yet and we can merely speculate. And although I am picking Aizen as the victor, a proper winner cannot be determined because we do not know The Sage's full capabilities and once we do, we might be surprised with his power.
And what about spiritual pressure and his shikai? i saw something like that from narutoverse at the early chapter of the manga (the chunnin exam) when a team of anbu use some kind of spiritual pressure against those gigantic lions in order to save anku!! even aizen dont stand a chance against the kyubi (nine tails) on a rampage!!!
@battleheiz: I think Rikudo would have enough Spiritual Chakra to prevent the crush, and the Shikai is just like a powerful genjutsu, Rikudo could likely break it, or counter with his own illusion. And little good Aizens shikai is doing now against Ichigo.