I have to go with Sasuke. The meat of Itachi's base arsenal is his genjutsu which would wreck high level opponents. Unfortunately it won't work on Sasuke. Itachi has better taijutsu, speed, and reflexes, but the fight will come down to ninjutsu not taijutsu, and he doesn't outclass Sasuke enough in that area to make much of a difference anyway. Plus Chidori Nagashi pretty much guarantees Sasuke the edge in that case. Their skills in weapons are equal so there's that. Itachi's base ninjutsu arsenal pales in comparison to Sasuke's. The only edge he has is his clones and clone related skills. I don't think that is really enough to overwhelm Sasuke. Then there is that Aoda, which Itachi straight up can't handle except by controlling, and I don't see Itachi doing that with Sasuke there. All he'd have to do is look into Aoda's eyes to break Itachi's genjutsu if that happened, just like when Itachi and Sasuke looked into each others eyes to break Kabuto's genjutsu.
Of course, I don't know how prime Itachi would fight or how strong he is. I'm not even sure if there is a prime Itachi, so my opinion that Sasuke wins isn't worth much.