I also recommend
http://www.thearender.com/cms/
Some cool points about TheaRender.
FAIR PRICE
Thea is built for the professional user but without an elitetargeted
price tag. It is affordable for one basic reason; we simply
enjoy working on creating a solid and elegant application in order
to meet your expectations.
VERSATILITY
Encapsulating more than one engine cores, your renders can be
as versatile as never before. Use fast photorealistic rendering for
animation or unbiased rendering for ultra-realism. Or bake
textures for your games and real-time architectural walkthroughs.
All these by a mature, stable and optimized renderer.
PHYSICALLY BASED RENDERING
From the basic materials up to the layer system and lights,
physical laws are obeyed, leading to superior render quality. The
incorporation of real data, such as material measurements and
industry standard lights, ensures that you will never need to think
or work in an “unnatural” way for your achievements.
PORTABILITY
The engine has been developed as platform and system
independent application with modern software architecture. The
application look and feel does not change when moving from
one operating system to another. You can simply connect
different systems for co-operative renders and take advantage of
unlimited memory usage and scripting automation.
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What is very COOL is that you can use Unbised and other biased techniques making it a hybrid of vray/mental ray and maxwell/fry etc..
Very appealing. Being able to stretch the bounds of reality if needed but at the same time being able to create physically based materials and lighting situations based on the visible spectrum and how we precieve light and materials.