Sasuke is a mid to close range fighter, not a mid longe range. His chidori has a limit to how far it would extend and his genjutsu is moderate from what he's shown thus far at best.
Neji is an interesting matchup for Sasuke. Sasuke would be able to use the Sharingan to mimic taijutsu manuevers and has the speed to keep up with Neji, but his Sharingan won't let him see the chakra points like the Byakugan would. Also, post time skip Neji is also a mid to close range fighter.
And I know Lee wanted to use Primary Lotus to defeat Neji, but he was never afforded that opportunity. But if I'm not mistaken, he did get to use a variation to defeat a certain Uchiha.
Genjutsu always seems to be the "end all" in most one on one discussions, but it is my belief that the Byakugan's perception of peering through genjutsu truimphs the Sharingans or, at the very least, is on equal footing. Chiyo saying what she said about fighting a Sharingan user would apply to those without amazing perception, which is what is required to see through genjutsu. After all, Deidara trained his normal eye to see through genjutsu.
Sasuke fended off Team 7, but...not really. Yamato wasn't trying to hurt him, Naruto was operating at a fraction of himself after going four tails, Sakura isn't going to try to hurt Sasuke...she's like some of his fans here turned up about 13 or 14 notches (and she's slow. What has she hit that wasn't a puppet or Sai standing still?), and the jury is still out on if Sai is useful or useless. Getting shocked and falling over didn't help his cause. So Sasuke beats up Sai, Yamato is about to get serious and...Oro comes in with the "let's get outta here". Sasuke did beat Deidara soundly which raised Deidara's coolness moreso than Sasuke's. That's probably because the "elemental" advantage was Sasuke's saving grace, and a lot of people thought that wasn't the best way to give Sasuke a win.
They're both pretty fierce. Sasuke has all his "power-ups" and Neji has his Hyuga training, but we haven't seen just what Neji is capable of. He fought himself off panel in the manga and that's it. But from what I know about him post time skip, he would have been able to defeat Hidan by himself and would have been a dangerous matchup for Deidara. Not sure about Kakuzu and I haven't seen anyone outside of Akatsuki that could have taken Sasori one on one.
But I'd say that Neji would beat Sasuke. Disrupt chakra flow = no curse seal use and limited if any jutsu use. Neji need only lightly tap Sasuke.
Sasuke's taijutsu? Won't work against Neji.
Sasuke's genjutsu? I don't think will work against Neji.
Sasuke's ninjutsu? Potentially, but not if Neji lands anything remotely near a shot.
And he would.