Well, as you eluded to, I've really enjoyed the V20 (and V10 for that matter). I've found the V20 to be the first phone that typically survives a full day for me without charging, and doesn't have any lag/freeze issues. I think the DAC quality is quite good, better than the AK240, and almost but not quite to the level of the AK320/380. The amp isn't quite as good, and partially that's due to their low/high impedance software auto-switching (i.e. have to hack to enable full amp performance with sub 50ohm headphones). I don't mind using the bult-in amp, unhacked, with my JH Laylas, but if I'm going to listen for an extended period of time, like on a plane, I will hook up a Pico Slim.
I've been primarily using Hiby Music, as I prefer the interface to that of Neutron. I couldn't say that there is any noticeable sound quality difference.
Especially with this phone going for as little as $300 lately, I'd say it's a great deal. It's without question the best smartphone I have owned, and the audio quality is quite good for being the device that's always on hand.
I could go on about the cameras as well, also the best experience I've had with a smartphone, and being able to develop RAW files on the fly has gotten me shots I never would have though possible on a phone.