Only Sasuke haters or Neji fanboys would say that Neji would win. Come on man. I'm gonna assume that Sasuke is gonna be strategic, if so, he wins, mid diff. He defeated Deidara, I don't see Neji doing that. Don't get me wrong, Neji is strong, he has a ton of potential, but Sasuke is too much for him. Sasuke's faster, he has a wider arsenal, he's a better strategist (never really seen Neji use strategy much). Sasuke would probably lose in Taijutsu, not certainly. He still has insane speed and 3 tomoe to dodge the Gentle Fist attacks.
It would be a great fight, Sasuke takes this. I just wish Kishi made a fight between the two of them in part 1. Neji was trolled.