Best I have heard with my NT6pro is the Paw Gold, but expect that the Sony WM1A/Z will best that pairing. Unfortunately, I am without my pro to even try until after CNY and then some. The Sony/Paw Gold are the SQ kings in my book and the Sony ticks all the boxes with even a 30 hour battery life. The AK380 is one league down in SQ IMO in a side by side listen at RMAF and requires an external amp to sound its best. However, the DX200 sounds like it may be a contender when I get a chance to hear it. My bet is on the Sony WM1A at $1100 USD or less used as the best in class - top quality UI, Build, and SQ.
The i5 is a great little DAP too for usability and good sound, but definitely inferior to the top dogs in SQ - but may be good enough if you get a great enough discount. The Aune M2 and Calyx M are cheap and have top dog sound, but are lacking in functionality if you can live with that. The Calyx M and the WM1A can drive HPs/CIEMs without the need for an amp stack if this is a concern for you - making them very convenient. In the end, I will likely keep my Calyx M and add a Sony A and the Aune M2 to complete my collection. If the DX200 can clearly beat the Calyx and the Aune, then I will trade them for the DX.
Remember, this is per my preferences and IMO so YMMV.
BTW, while the MOJO is definitely a top dog device in SQ and build, it was not that musical to me and unable to beat my AK100ii/BH2 stack in SQ so I passed on the purchase. I find that the MOJO is particular in its paring and didn't work well with my NT6pro for my tastes. What I look for is musical realism, euphonics, with thick natural notes, on stage presentation, and right sized instruments that get my feet tapping. If you prefer a two sections back presentation with a delicate thinner analytical details with lots of air, or are primarily a classical music fan, then the AK380 may be your go to device.