Unfortunately I don't have them all at the same time, but I could explain a bit as to why I sold them to the best of my memory.
Before I start I must explain that I have a few "deal breakers" that specific to me so it might or might not apply to you lol. Another thing is that I also like the Grado house sound which is a love or hate type of signature, so this further solidify the "this might or might not apply to you" LOL.
My current daily driver is SDAC, I like SDAC because female vocal is forward, that's my number 1 priority. After that I think SDAC has emphasis on upper mid / low treble which makes female vocal pop forward as I previously mentioned, but it also emphasize a lot of string instruments which I listen to a lot. To me this dac has the female vocal I like and the rich mids.
MMB2 has the same forward female vocal, actually it might be EVEN more forward. So I was really happy with it for a while since that's my number priority. But after a while I realize the presentation is a bit more on the lean and clean side, where I wanted a bit richness / thickness in my sound where SDAC do better. For example string instruments isn't emphasized on the MMB2, it's not recessed either, but rather it has a neutral presentation. But I wanted more emphasized.
Thing with Draco is actually the opposite, where the female vocal is laid back, also its treble presentation in general is also more laid back. If MMB2 is more upfront and center then Draco is more relaxed. If you like a darker more relaxed and wider presentation then Draco is for you. Also to me it feels like some information is missing in the name of smoothness.
Ultimately despite the resolution is lower than the other 2 but I still went back to SDAC since it has the sound signature I like. I also had Denafrips Ares II during the time I had Draco to compare side by side, but I end up selling that too LOL.
Again I might be the only you know in existence that would make such ridiculous choices. So your mileage may vary.
Definitely let me know if you have any questions!