Interestingly enough, I know of an amplifier designer (a long standing NZ brand at that) who noted to me that he would always prefer a well made glass-fibre toslink cable.
The rest of the cabling in his lab was run of the mill. From a theoretical point of view, he preferred coax to optical as there were issues at the time we talked, where the optical output of the Apple TV3 was causing audible jitter issues with some of the amps on the market... But he believed it was due to poor implementation at Apple's end, than the amplifiers handling of the signal. Interestingly enough, Apple TV2's didn't suffer from the jitter issue (it manifested as a loud CLACK), whereas the ATV3 was notorious for it.

For the record, he said the best thing to do speaker cable-wise, is to stick with the same cabling through out the system. That is, using the same copper in the amp, speakers, and of course the speaker wire itself...
If you have speaker cable in your speakers that's worth $2 per meter, then buy that for the rest of your system.
If you ever open up old speakers, you'll often find the cabling has badly 'greened', meaning the corrosion has change the impedance of your speaker. Re-cabling the speaker internals will go a long way to bringing the speakers back to their original level of performance. Many speaker manufacturers have changed their cabling over time, having suffered issues with gradual drops in performance.
Interestingly enough, a few I know of now have silver cabling inside.