BCD-1 > BNC > BDA-1
I use AES for my BDP-1. Easily switchable to BCD-1 behind rack, but I don't hassle with it.
The problem with optical is that the optical signal still has to be converted back to an electrical one at the DAC. An addtl step and an addtl opportunity for error to occur (jitter?), I think. Not surprised that AES sounds better.