In all honesty, the results between the two programs will vary DEPENDING on who is doing the work and the skill level involved.  I personally prefer using DAZ Studio instead of Poser but I own both, yes I mean P8, and I know that if I wanted to and invested some time, I could learn P8 a lot more and render in it.  But I wont and its just a personal preference that is partially determined by the UI.

 

Here is a link to my gallery over at DeviantART - http://mattymanx.deviantart.com/gallery/ - you may judge for yourself as to the quality of the work. 

There are seven images near the top that were rendered with LuxRender via Reality, all the rest are DAZ Studio 4, 3, 2 & 1.  Except for the two Poser renders and the on Carrara render.