gaara with only gourd sand was doing well to counter uchiha sasuke whod fodderise these two in seconds. he had a roof fall on him and he just tanked it. plus we know even SRA gaara would crush Lee as he got stronger and lee lagged behind due to his injuries.
Gaara without much difficulty. I'd give this fight to him mid difficulty at best. It is clear that Gaara is on a whole other level compared to these two. In part 1 this would be a good fight but right now it is obvious who will win.
Basically Rock Lee is fast but if genin Gaara could defend against him then Kazekage would have no problem. Neji can prevent himself getting sand coffined with gentle fist full body blow and rotation.
This range is also very long and ideal for Gaara who is a long range attacker. Lee and Neji are taijutsu specialists so they can't attack at long range. Lee could cover the distance but he hasn't showed any improvements unlike Gaara who has shown loads of improvement.
Yeah Lee didn't show any gates further than in P1 chuunin exams, so Gaara can certainly suvive anything he throws at him now, and Neji is crushed sooner.