are tosslink cables all the same? I mean is there different sound characteristics between different brands like there is in interconnects, power cords, and speaker cables?
Longer is better. more than one and a half meters. Glass is better than plastic fibers.
Some of the best glass fiber ones are pretty cheap medical grade for $15 or so.
1.5m is better for coax, not Toslink.
Sonic Wave by Impact Acoustics is a glass toslink that offers great performance with value pricing.Two meter pair can be had for 35.00 on Amazon.Great build quality with a lifetime guarantee.
Yes, different brands and models of Toslink cables do sound different. I've tried two different brands in my system and one sounds brighter than the other although they both sound very good.

I recently acquired a couple Lifatec Silflex cables that performed with admirable results.