The two NOS DACs I'd compare (I have both and like both on separate systems) are the dbaudiolabs Tranquility and the Tranquility SE.
I agree, it would be very interesting to get a collection of NOS DACs in one room and over a period of time listen to all of them and create a ranking based on clarified criteria.
As to best (or "King") my vote would be for the Tranquility SE. Of course, quality power cord, quality USB and single-ended interconnects, computer-server, playback software, etc. become more and more crucial the better and better the DAC. The price to performance of this DAC is quite surprising to the upside...
just my opinion and experience,
:) listening,
Ed