I think Toslink is still most likely to be an inferior interconnect. It has two extra stages in conversion that are unnecessary. Also, for most companies it is an add on just in case… so stock electrical -> optical and back. It is not so much the transmission media but unnecessary conversions.
SP/DIF has been the oldest and used for decades… then USB… needing completely different receiving processing and optical. AES is a newer, made for high end audio which I thing is just balanced SP/DIF connection.
As far as connections, in general, AES… preferred, SP/DIF , then USB (depending on DAC) then optical.
If the DAC is optical only it is likely an inferior DAC.