it depends ...
In general, they're both very useful and attractive namespace "real estate" - short, memorable, brandable, .com, very rare, and currently enjoying decent amount of market buzz.
but IMO it's going to be really hard to beat something like "DoMy" in terms of commercial potential - many compelling possibilities obvious for that one. QXV has decent "branding" potential, but hey maybe someone will offer me QVX for $500 less - I'll take that one instead (and probably would actually prefer QVX even for $500 more, come to think of it.)
"Do My" pronounceable in 2 comfortable syllables vs. 3 for "queue ex vee"
Dooo Myyy nice smooth sounds, easy on the throat - subtly risque connotation but that's okay for a web 2.0 application - in fact would be perfect brand for a web dev related business - "do my dot com"
Queue Ex Vee on the other hand might present a strong, decent "business" image
It would be selling QXV a bit short to insist that the only possible end user would be the elusive Dr. "Quentin Xavier Vanderlay" (he's out there somewhere, don't laugh!) or okay maybe something like "Quality Xylophone Varnish" would fit too ... But treating it strictly as an "empty vessel" without meaningful acronym probably will take some additional branding effort.
seems like "Do My dot com" is going to be hard to beat here ...
Not sure if this is already reflected in current reseller market price for a brandable premium CVCV (let alone the rare case containing 2 short dictionary words) vs "low-frequency" LLL ... but in this particular case I think it would be, possibly by a substantial margin.
