Your free to use any image rendered in either Poser or Daz Studio for any purpose even commercially with any items purchased through either the Daz Store or here at Rendo. Some free items may have a caveat for personal use only.

I personally find the Daz experience easier then Poser but it really is a personal thing I guess. I used Poser 4 a long time ago and still have v10 installed. I just prefer the Daz Studio Ui and the ease of install with DIM. The figure compatiblity for clothes extends across both apps.

its hard to say which app would be best for yourself as it usually is a bit of a feel thing. I just find some the Poser interface to be awkward but ive spent quite a lot time familarising myself the the daz studio ui. But you wouldnt have to look far to hear someone say the exact opposite :)