Again depending on your equipment I would do a test to actually see if one seems to perform better from an audio standpoint. It's nearly impossible to tell in a scenario like this for most consumer gear how good either interface is.
"Limitations
The receiver does not control the data rate, so it must avoid bit slip by synchronizing its reception with the source clock. Many S/PDIF implementations cannot fully decouple the final signal from influence of the source or the interconnect. Specifically the process of clock recovery used to synchronize reception may produce jitter.[7][8][9] If the DAC does not have a stable clock reference then noise will be introduced into the resulting analog signal. However, receivers can implement various strategies that limit this influence.[9][10]
TOSLINK optical fiber, unlike coaxial cables, are immune to ground loops and RF interference.[11] The fiber core of TOSLINK, however, may suffer permanent damage if tightly bent.
S/PDIF is unidirectional, so it lacks flow control and retransmission facilities. This limits its utility in data communications."
