optical is better in theory (especially for long pieces, like anyone has a fifty foot run from dvd to processor :-)) because it can move data faster and suffers no interference, but from my personal experience it makes no difference. one thing to keep in mind with an optical cable is they can break more easily than a dig. coax and youd want one with a snug fit into your components. any cable with some play in the connector could end up with the cable not lining up properly. as for sound quality of them both, i cant ever tell the difference. i think most people probably pick one over the over based on how many inputs of each that they have; you wouldnt want to tie up your last dig. coax if you had 4 free opticals and vice versa. luckily now a days most sources give you an option, even my hd cable box from time warner has multiple outputs (a small victory for mankind). oh and i am comparing sound quality using top of the line dig. coax compared to top of the line (price wise) optical cable, not a turd dig. coax and a nice optical :-).