I recently moved from BluSound Node2i to a Lumin U2. I am absolutely blown away by the sound difference, much more than expected. I'm an electrical engineer that focused on embedded systems so I didn't expect this should have made any difference since I also used an external DAC (like you're doing) and extracting a bit-perfect copy of the data of the signal at the DAC really shouldn't be very difficult for audio data bandwidth. I tried it really for fun with some hope that maybe it would help a little bit.
I am still star struck with the improvement in the sound and sound soundstage. I can't really explain it and have kind of lumped it in the "black magic" category. But whatever the reason for the improvement, I love it.
I'm sorry I can't actually answer your question (comparing the 3 brands) but I can give a solid vote for Lumin - so far anyway. It's only been a month or so but it's been solid. I am a bit nervous about the possibility of the company failing, but that's true of any high-end audio company, especially smaller ones. Their app is OK but not amazing. I am using Roon on it for now mainly, but sometimes I switch over and use their app. I actually use Amazon Music (free trial) and Lumin supports it natively (unlike most and disappointingly, Roon). I will say that the overhang in the back (to hide the connectors a bit) is more annoying than expected. Mostly it doesn't matter, but unplugging the XLR is a rain pain if you have larger fingers - the lock is very tough to engage while pulling out the cable). So if you're a frequent cable switcher and use XLR, that is a negative.

