A & K is the best in this list. As for me even A&K Jr has better sound that onkyo .. more deep, more clean and much for power.
Buy when price matters - take a look on Centrance dac http://centrance.com/store/#!/~/product/category=7071966&id=68400127 it gives best sound i heard under $1000.
Personally I feel the Onkyo, despite being the best, is just far too expensive. I think the DX80 is a good alternative from iBasso with a bit better specs to the 50 & 90 its shaping up really good. Although one thing that I find really appealing with the Onkyo is the android OS, its simple well-known and visually appealing with plenty of customization.
The Onkyo is the most interesting of the new DAPs coming out. It would be nice to see it get some more love. At the price point it could offer a better package than the competition. Independant info on it still seems a bit rare though. In English at least.