At my hi-fi shop, I have the choice between those two "budget" DAC. I mainly choose this one because I need both USB and optical inputs (using my PS3 as my bluray device and my PC as my music source)... but I could go with an optical input only DAC if it's cheaper and has the same overall sound quality.
However, I can't see any direct comparison between those two. People keep telling that the V-DAC II is clearly superior in every way to it's predecesor. However, as the V-DAC MkII is 399$ here, I can get the V-DAC at the same shop for around 250$. I know that the MkII has an asynchronous USB input, better stereo separation and lower distortion, but is it an audible difference overall as I will only have an entry level integrated amp (NAD C 326 BEE).
Do the V-DAC II worth almost twice the price of the V-DAC? I don't care about the... look, as it will mostly be hidden where my computer is. If anything, I could put that 150$ difference on better speakers than my RTI6...