It's all about the lighting.  The reason Luxrender renders look better is because the user is usually lighting a scene with emitters, and more physically accurate lighting systems.  Poser, however, is now capable of quite the same.  Poser actually has an edge in the materials department, as SSS can be more definable for realistic skin results.  I could light a scene using spotlights and send it to Lux and not mess with the materials at all, and the results will look strikingly similar to a Poser 4 render.  Simple as that.  I love Lux, not specifically because of the results, which I could also attain in various other renderers, but for other reasons.  Lux allows you to change light gain and turn off and on lights in the scene as the render is in progress.  You can't do that with most other renderers, especially Poser.  It really helps evaluate your lighting on the fly.  That's reason alone for me to use Lux for more than  half the images I've been rendering recently.

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Tools :  3dsmax 2015, Daz Studio 4.6, PoserPro 2012, Blender v2.74

System: Pentium QuadCore i7, under Win 8, GeForce GTX 780 / 2GB GPU.