What's the best non-DAC streamer?

Roon lifetime is $699.

The sonicTransporter i5 is a "small, fanless, NUC with a decent processor including wifi, a small amount of RAM, and a small internal HD for the software."

For the non-DIY hobbyist, it's put together, configured, optimized and with Roon software installed for a couple hundred bucks more.

I realize the OP is asking for something under $3k but, in general, the best streamer cost no object is the Sonore Signature Rendu SE optical. The Innuous and SoTM are cheaper and still sound very good.

But more on topic, I think the best value is the Sonore opticalRendu Lite for Roon. It sounds better than the Innuous and SoTM and is lower cost. It's also the only streamer in that price range with optical networking.

If you go with a Roon server get a NUC with an i5 , 256G M.2 SSD and 8G of ram. It will be about $300 cheaper than the Small Green Computer. Don't worry about assembly and installing ROCK Roons OS a trained Chimp could do it. Just follow the directions. 

If sound quality is more important to you than feature set and interface, you could could consider making your decision based on synergy instead.  

The Auralic streamers as well as many of the popular Chinese streamers are known to be neutral to bright (in a good way).  So they would pair well if you have a tube amp or tube pre to create a more balanced sound.  

The Innuos and Lumin products are known to be slightly on the warm and refined side.  I have a Lumin D1 with Sbooster and I can confirm this to be true.  These product are more likely to pair well with solid state gear.  Although I have found the Lumin D1 to sound great with both McGary amp and MicroZOTL pre combo, as well as all my solid state pass amps

Thank You @hgeifman  for your concise notes . It will help me to as I am going through the same process as the OP . I also do not believe I  need to spend as much. The other interesting post was @rockenator referencing the interface . Also I plan on using Qobuz for the my more critical listening when streaming.