For me the biggest advantage of DS over Poser is (IMHO) it is much easier to pose figures in DS than Poser.  And that is one of the biggest hair-pulling frustrations of dealing with these types of programs, getting the figure posed correctly, right down to the fingers and toes.  When DS came along with it's various new ways of posing, I thought it was the greatest thing since sliced bread.  And I've been using Daz Studio ever since.

I still fire up Poser once in awhile for exporting scenes into Vue.  Which happens to be one of the big negatives with DS, it doesn't play well with other software.  So it's kind of a toss up for me.