From what I've seen, my favorite renders have come from Lightwave and Cinema 4D. I have also seen some very good renders from Maya. I don't like Bryce renders, personally, although a few were pretty good. One thing you can do is cruise for some nice light sets. Blackhearted has a light set in the Renderosity marketplace that works true wonders for rendering within Poser. There are also some good free light sets, for example the set by Anton in the free stuff section is very good.