Neji wins mid difficulty.
Neji has trained with Lee and GAI sensei for years. He's accustomed to very fast speed and taijutsu at extremely high levels. We're talking about GAI! The guy who defeated Kisame, uses a wide array of weapons, and can open all of the inner 8 gates. He's already proved to be one of the STRONGEST characters in the WHOLE manga. Plus, he rivals Kakashi who is Sasuke's sensei.
Neji can deal with Sasuke's "Rock Lee" upgrade, and no taijutsu Sasuke has should surprise Neji. Neji has dealt with Rock Lee, Gai sensei, and even all out attacks from Tenten.
As far as taijutsu goes, Neji >> Sasuke.
Most of Sasuke's attacks can be easily avoided due to Byakugan. Neji can see when chakra builds up in Sasuke when he tried to use Katon. He can see if there are shuriken hidden in flames if he tries that trick. He can see exploding seals. As far as his fundamentals are, he's probably more sound than Sasuke when it comes to using kunai. He does train with a specialist (Tenten) as well.
The only things Sasuke has in his arsenal is Chidori. No one knows whether or not it'll work, but if you ask me, Kaiten > Chidori. Unlike Gaara's sand, where he's just a STATIONARY OBJECT, Neji is actually moving and ROTATING. Although it may be bias, Gaara does NOT REFLECT attacks. From all we've seen, his sand just BLOCKS. But Neji has been shown to not only block, but REFLECT. The proof is right there when Naruto tried to attack Neji. About 5 Naruto clones tried to jump Neji and what happened after Kaiten? They ended up flying 50 yards away. With that as a premise, I can see Sasuke trying to use Chidori, only to be blown away. And that becomes a waste of chakra.
And just to end the discussion, Neji only technically needs ONE hit. It doesn't even have to be at a chakra point. Just a flat palm to the heart is enough to suffice. The fact that Neji can one hit KO sasuke pretty much means it's like Neji has Chidori himself. Chidori is a hit hit kill move, yet Sasuke can only use it twice due to chakra. Neji can probably use HUNDREDS of gentle fist palms, which would be similar to having 100 Chidoris. Sasuke does NOT have a form of defense like Neji and Gaara.
Even if 3 Tomoe, I would still say Neji takes it. You CAN'T BLOCK GENTLE FIST. It goes internally. Sasuke would literally have to avoid Neji touching him at ALL, which Sasuke wouldn't be able to do in his state.