Which is better Coax or Optical cables

""But" if a person were to place a DAC between the Oppo and integrated there would be a need one."

True, however it’s not as simple as adding the DAC and cable. More often than not it becomes an exploration to find the right combination that compliments your system. Have you considered other paths for upgrade?

My vote would also be coax. So many brands available, but I would add Black Cat Cables to your list. These are designed by the same guy that designed the Illuminati digital cable.