Network streamer recommendation without a dac/amp (pure streamer), under $4k

Out of those go with the Lumin... rock stable GUI and solid support

Agree of those three the Lumin.

Do you think the fact that it doesn't have a big toroidal supply puts it a step behind bdp3?

Although I can get one that accepts sboosters PSU which will raise it up.

Personally I do not see the value-add (including sonically) of spending more than 600 usd/euros on a network streamer when all you want is a transport using the digital out connections (USB, SPDIF, Toslink) to connect it to a dac/preamp.
I have 3 network streamers which I use as transport to my amp/dac:1) Auralic Aries Mini with a 1TB SSD installed internally (with all my music files) which functions also as a Music Server/NAS at home. I use the USB out connection to the DAC. Works great and great app. (price around 500 euro if you can still find one).2) Cambridge Audio CXN. Also great but only has Spotify & Tidal streaming services (no Qobuz). I use the SPDIF output.
3) Raspberry PI 3B+ plus HifiBerry Digi+ for the SPDIF output. I use Volumio software. Works also great ... although you have to pay yearly fee if you want to connect to Tidal/Qobuz native. I use SPDIF output. RPI & Volumio app works also great.
All 3 work great ... only downside of the Cambridge CXN is no Qobuz.

Bryston BDP-Pi is basically the same as my RPI+HifiBerry Digi+ ... so why spend more?
And the Auralic Aries G1 & G2 are basically the same as my Aries Mini for a lot more money.Too bad Auralic stopped selling it after they established their brand name and realized that there are a lot of people out there who are willing to pay a lot more money for basically the same functionality/performance.

I would certainly also look at the Bluesound Node 2i ... great value for money (@ 549 euro).

The Yamaha MusicCast NP-S303 is an example of a network streamer that simply does what it is supposed to do. And for the price of 379 euro. If you look-up on the internet what this unit looks like on the inside of the box, then you'll realize how simple a network streamer transport unit really is. And you can assume the unit is of a good quality as I seriously doubt that a company like Yamaha would do anything with would create any reputational damage to their brand / company.

However if you really want to spend a lot of money on a network streamer, then I would go for the Aries G1 or G2 (if you want to install an SSD internally) or the Lumin U1 Mini.
By the way, the Auralic, Lumin, Esoteric and Linn control apps all use the same OpenHome Linux software platform as the basis for their own control apps. ;-))

@ajlm I think its because different streamers (like different dacs or amps) have different levels of quality and lead to different sonic performance. Of course this may be false and I haven't verified this myself since I have only heard 1 streamer (SOTM 200 ultra). But from what I've read the consensus seems to be something like a BDP3 or Lumin U1 mini will be much much better than a blue sound node 2i.