Ayre QX-5 vs Lumin vs dCS Bartok

Of these 3, which would you go with?  Building out a new system with Roon and one of these as the digital hub.  I like the Ayre AX-5, and am leaning towards the QX-5 as a matching component.  However, the others seem a step above, please share your thoughts.  Thanks.
I have owned the Ayre QX5 and the Lumin X1, but have not heard the Bartok. I owned the AX5 Twenty when I had the QX5, but have now moved on to something else, although the AX5 Twenty is a great amp.
Both the QX5 and Lumin are great dac/streamers, and I doubt you would be unhappy with either. I preferred both to the Chord DAVE/M Scaler I owned previously.
The QX5 has a big, detailed, powerful and muscular sound. It can sound very slightly dry (as can the DAVE) and has a tonal balance just a shade lighter than neutral, but I think this is just consistent with the Ayre sound, since the AX5 has similar characteristics. It is very engaging and I often found listening to it that I had a real sense of the recording acoustic and the presence of the musicians.
But ultimately I preferred the Lumin X1. It has a bit less of the "master tape" realism but is tonally a bit warmer and more colourful, and has a more liquid, saturated sound.

It's really down to personal preference. If you like the Ayre "house sound" and prefer a big, airy soundstage rather than a warmer, slightly darker presentation, you may prefer the QX5. The QX5 is also a great match with the AX5. I preferred the tonally richer and more liquid sound of the Lumin, but sometimes still miss the QX5.

Put MSB Discrete DAC in your list. It has MSRP right under $10K. The second optional power supply is $1,500. The Renderer module about $1,500, and the ProUSB ProISL module combo about $2,000.
I can put in a good word for the Ayre.  I owned the QX-5 Twenty for a while and really enjoyed it.  I found it to be one of those "just works" pieces that never gave me any trouble and always sounded great. I used the network input as a Roon endpoint, the balanced headphone outputs with my Focal Utopia, and the balanced preamp outputs with my Genelec 8030C monitors.
Surprised this thread didn't go further.  I own the AX5/20 (selling as I have the Vandersteen HP5 amps in bound).  I owned the QX5/20 and LOVED it for so many reasons.  Just a great digital hub that sounds great.  The Lumin is also a great DAC and I agree with the first posters answer in the differences. I personally like how 'fast' the Ayre gear is.  It is so revealing.  Whenever I change out and try something else, I realize that over the long haul, I love how detailed and still musical the Ayre gear is.  Personal choice and I'd be happy with either.  

I have auditioned the Bartok on many occasions and feel it also is a nice DAC and worth the price of admission.  I don't feel it's better than the QX5/20 though.  

I own the QX5/20 and have used it for a while as a Roon endpoint on my network with an i5 core in another room.  Very nice sound much like @rossb describes.  Recently added a Wolf Alpha 3SX server to my rack and connected it by USB through the Wolf’s reclocking USB output.  I did not know the Ayre QX5/20 could perform at this level...  very rich tone now as well as the previously noted air and detail.  Much more muscular in presentation. 
I"ve heard it in uber systems and it's a great DAC/digital front end.  I will scale with better equipment to a very high level.
as above, if you are searching for a musically rich tone, look no further than the QX-5.
Happy Listening!
Funny thing is that I don't know anyone who have heard the QX5/20 not enjoy it and feel that it punches well beyond it's price range.  There is a reason that Ayre is taking it's time with a reference DAC.  
Thanks everyone.  Purchased the QX5/20 and have it on order.  No looking back, this should be great sound.
I use Roon via ethernet to my QX-5/20, with balanced analog to a KX-5/20 preamp and VX-5/20 amp. Of course the sound is great, but just clicking play on my computer and watching the AyreLink turn everything on is a fascinating convenience. A DX-5 DSD handles Blu-ray. I’m hooked on the Ayre sound, or perhaps the absence of it that results in transparency.