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

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.

To GDhal .Anything Schiit does Mike Moffett knows his S..t.
Oppo 205 decent dac for the $$ personally  the PS Audio 
Offers this I2S as a $800 add on board which is total B.S.. 
I recently bought their top Direct stream dac ,that is a Excellent buy 
With free firmware upgrades,the latest Huron was Very good.
When you are buying a $6k dac Retail can be bought for $4k .
Total rip off to not include board for I2S  board.if you are using s digital player make sure it has one most do not. They do claim it 
Sounds a bit better .i will never know ,just on principle.
One more thing I have tried a Bunch of good USB cables I like the 
as Diamond a lot. There is a U.K cable that is more refined and a bit richer at the $1200  Mark still testing it