poser7 is good for posing human figures and not for rendering IMVHO.
carrara is not as good as poser for posing human figures, but is good for rendering.
FFRender (poser7) is at about the same point in its evolution as carrara 1 or 2.
poser 7 shader trees are as good as carrara shader trees, but differ in some ways, and the former are too complex for default users AFAICT.  poser 7 shader trees will be even more feature-laden in poser 8, if past experience is any guide, and I also hope they have already jettisoned FFRender for something else.