Which is better Coax or Optical cables

Use Coax never optical unless absolutely necessary. Just think about whats happening to the digital signal and conversion losses, it matters... 

Caution: The optical inputs are not recommended for DSD or for sample rates above 96 kHz. Optical connections may be unreliable at sample rates above 96 kHz.

Coax. Is this even a discussion?

http://silversonic.com/docs/products/GlassMasterToslink.html

Give it a try.... Money back Guarantee if you prefer your Coax, but feedback tells us this is a more "analog" sounding cable.

Coax...stop debating it already.  Toslink is inferior.  AES/EBU is another matter.