I don't think you can say one player is clearly inferior or superior to another. I don't like to sound defending DX50 over AK1xx because it is clear, personal preferences and subjective bias plays a huge part on these discussions. To my ears, headphones I use and the kind of music I listen to DX50 wins over AK100 hands down. Paired with a very good amp a DX50 can beat the AK120 SQ-wise.
I almost pulled the trigger on AK120 once because it looks cooler than DX50 and at the time the dual-dac, dual uSD and 64GB onboard memory was attractive to me and I was willing to overlook the 6x price difference. But no matter what music I played on it I can't tell the difference with DX50+amp and an AK120. Sure there are a some songs which sounded better on AK120 (mostly acoustics and strings) and it's not a huge difference. But most tunes I listen too which are quick tempo and lots of low end details (rock, metal) sounds superb on DX50 + amp, and thin and hollow on AK120.
True DX50 has been through a crap load of bugs and issues. I even waited until batch 7 and FW 1.2.2 before I dipped my toes when the annoying bugs I can't live with were fixed. Still I've been through several annoyances like changing SQ with succeeding FW updates. and the basic feature which seem impossible for iBasso to fix, the gapless playback. But all those things never got into the way of enjoying my music.
I also agree that none of the iBasso's stock FW are neutral. They have a hint of warm sound signature and on some FW, an elevated bass. But, if you want to hear what is neutral in DX50, and if you can be bothered try it with rockbox. True to it's core objectives, Rockbox comes neutral by default and indeed gives DX50 the neutral sound signature that many seek. It goes to show the underlying hardware very well built. Software is what pulls it down. Crashes, volume spike and other UI issues I believe have not yet been reported by those who installed RB (although I never encountered them personally on stock FW)