You can't go wrong with the Vue/ProPack combo.

Bryce is DEAD IN THE WATER.

DAZ Studio is a long way from being released, and even longer until you will be able to do anything but render with it.

If P5 had plugin support(besides the ridiculously priced Reiss Maya plugin), I may recommend it over P4.

In any version of Poser, rendering is slow (P5 is very slow). You will most likely want to render in a different app. P4 doesn't raytrace, but with the Propack plugins, you will be able to do it in Lightwave, Cinema 4d, or 3DSMAX. If you are(or think you may be) serious about 3D graphics, then at least one of these should be on your wishlist.

Again, and as others will suggest, Propack and Vue will probably make you quite content to sit in a dark room night after night being creative.

Mark