My $0.02, and I'm sure other will disagree. I always prefer coax, and here are the reasons why:

1) Coax cable is physically more rugged. Fiber optic cables are much easier to "break".

2) Sending a digital signal via the optical cable requires 2 additional data conversions: electrical to optical, and back. More opportunities for introduction of jitter.

3) I have heard references to "digital fog" when people talk about optical. Of course, that might go back to Stereophile.

4) My admittedly uninformed knowledgebase says that cheap DVD players and CD players only have optical outputs. Have to go more expensive to get both.

But at the end of the day, I have actually used both, and I could never hear or see a difference between them.