Neji has the Byakugan and Gentle Fist. He can see and sense all movements in an angle of 360 and is able to prevent someone from accessing chakra by touching them or kill a person by putting chakra to their heart or head. He can release Chakra anywhere from his body.
The Third Hokage in this battle does not know about Neji, Gentle Fist or the Byakugan. He cannot use Enma or Minato’s Death God Seal.
Who wins? My money is on Neji becuase the Third doesn’t know about Gentle Fist and the Byakugan, plus he is old and eventually experience fatigue.