Byakugan is Neji's whole thing. Take that away, and you have....nothing. But even with Byakugan, I still think Lee would win. Why? Look at the battle between Kisame and Guy.Who will win in a one on one fight between Lee and Neji without any pills and without Neji's byakugan and without the inner celestial gates
The only difference isDefinitely Lee. Neji relies on his byakugan just as much as Sasuke relies on his sharingan. Lee only uses the gates in dire situations. He's still extremely fast without them and his taijutsu is always incredible.