So does it mean that Hinata's Byakugan surpasses Neji's?
It's difficult to tell.
Arbitrarily taking both Hinata's 10KM and Neji's 800M as being relative indicators of their visual limitations, there are multiple facets to consider. I do not have the manga scans - but I recall Neji being hailed as a genius, skilled user of the Byakugan - having worked out many of the Head Branch techniques on his own.
He could have inferior vision, even inferior abilities, and still have superior skill in the Gentle Fist arts.
Hinata's role in an espionage and pursuit team would have likely driven her to develop her skills with the Byakugan to have superior range. Neji, being in a direct combat role, would have logically pressed himself to develop his skills for use at closer ranges.
It's also unclear exactly what the caged bird seal does in terms of restricting branch members. It's possible that it actually inhibits more intensive functions of the Byakugan - which could place a considerable limit on Neji when compared to Hinata. I also theorize that proper development of the Byakugan is tied to development of the optic nerve; if the seal functions as an inhibitor for the Byakugan, those sealed with it at an early age may never be able to develop full/'proper' use of the Byakugan. Though that applies logic according to known medical research - something that has no bearing in the Naruto Universe (and that logic can be directly countered by Ao, who had the Byakugan implanted... though one could argue that it is possible his perception of the activated Byakugan differs from a blood-line Hyuuga with a properly developed optic nerve... but that's reaching well beyond the canon).
Hinata has displayed a few techniques that Neji has not. The Gentle Step, for example... which we didn't get to see much of because she was up against the Naruto equivalent of a nuclear bomb. Exactly what that does is anyone's guess (though I'd imagine it plays hell with the opponent's chakra network like most Hyuuga techniques).... though this is straying a bit beyond "who has the better Byakugan."
Perhaps it is similar to the individual peculiarities that make each Sharingan user distinct. Shisui had his crazy special ability. Itachi had superb mastery over Tsukuyomi. Sasuke has exceptional control over Amaterasu. Obito apparently had Kamui (though I don't recall whether or not this can be acquired by others).
While I'd rather not see the Byakugan treated with the same careless plot development as the sharingan - it is certainly possible for there to be individual variances that make a "who has the better" discussion one of situation and circumstance.
