What's the best (or is there a "best") DAC input to use?

BTW, Firewire was good

the future is not always better

AES is best in my particular setup.

I have tried almost every connection for a DAC.  Of course, it depends on what the DAC will accept, but over the course of at least 100 DACs, this is my take on the best:

1.  I2S
2.  Firewire
3.  AES/EBU
4.  Coax with BNC
5.  Coax with RCA
6.  USB
7.  ATT Glass Fiber
8. Toslink

Very enlightening responses by all. Sincerely appreciated. Besides the fact that the DAC itself often wouldn't have every conceivable input, the transport also wouldn't have every conceivable output. Amazing how this hobby's possibilities and the quest for audio nirvana is seemingly never ending, because given the responses thus far, finding the right combination of DAC, transport and cabling between the two can be rather challenging. 

I2S IN THEORY CAN BE BETTER THEN ANY TYPE OF USB
For on the 5v wire potential electrical noise ,depending how well it is isolated.  If your dac does not depend on this method  then 
It can be as good  . Ps Sudio has tun this debate for awhile.
EVEN their very gifted Digital engineer Mr.Smith agrees 
Both are close .BNC can be excellent also everything comes down
To how well the Digital products deal with every facet of the  signal. Both Digitally,and Electrically.