I have had good luck with Indigo, Kerkythea, Lux Render, Yafray, Blender, and Sunflow. All free, some open source.

Kerkythea imports MOI obj with no issues. I was then able to set up a scene and assign materials easily. With most of the others, you need to import into Blender and then export to the other renderers (of course you can export from most commercial applications to Indigo, Lux, Yafray, etc, but that defeats the purpose of a free renderer.)