What's the best non-DAC streamer?

the best is DCS bridge. end of story.

I attended the XFI Premium show in Holland last year where Aurender and dCS were sharing a room. Being interested in the dCS Network Bridge I waited for a turn to speak to the rep. and whilst chatting the Aurender rep joined us and to my astonishment agreed that dCS was better. To be fair, it was busy in the room and I am not sure which Aurender unit was being considered.

My interest was turned into resolution when visiting some of the very hi-end rooms and noticed the dCS NB being used in 2 of them. Speaking to one of the owners, he said he has tried all the others. Still waiting for a used one at a good price. Not many around though!

Auralic Aries G1 = Transparent sounding (High resolution, not much bass, perfect for tube amp.

Intel nuc i7 with Roon rock = Close to Aries G1 but you get more options doing DSP and upsampling.

Innuos Zen MK3 = Best of them all, the tonal balance is great with the right amount of bass region. However, there's no official app for Innuos. You will have to buy roon or others anyway.

I owned 3 of them (already sold the G1). At this price point, Zen mk is the best.

I did try Aurender but it cannot use with Roon. Very disappointed about this. People may say its Conductor app is better than roon in sound quality but we all know ROON UI AND EXPERIENCE IS THE BEST IN THE INDUSTRY.

I have had good experiences with with Pro-Ject Stream box S2 Ultra. 

It works well with Roon and sounds nicer than running the core to your DAC direct.

After using a home-built PC with various tweaks to the OS and USB cards and a linear power supply, I’m happy with the exaSound Sigma streamer connected via Ethernet and with the same 12v LPS. 

https://exasound.com/Products/SigmaStreamer.aspx

It does MQA, DSD, Roon, etc, and has a couple of USB ports to hook up a disk drive for ripping, or an external  or  flash drive or storage.