I have the Joying UL135… NO the UL135N2. mine is still the arm version, not the Atom CPU. mine i the MTCD variation with Android 5 not the MTCB that has 4.4.x
I could not get your board to work with the joying unit. I could use it as a launcher, which would be great, but as soon as I plugged in my ALDL cable it would crash.
I am not sue the Joying is the best either, honestly if some of the features were on the NU3001 I have, it would be the best of both worlds. the screen on the joying is great, couple that with the ODroid, it might be a good DIY set-up.
I forgot that the DAC was not stereo on Android 6. wonder if Timer fixed it in his package