First, the default lights are crap.  You should be rendering with raytracing, defaults have depth mapping.  Miss Nancy make a very valid point, however, you did not mention using material GC which can possibly account for the some flatness.  But you will need to enter the material room an check your shaders; any transparencies, bump, and displacement maps must have their own GC reset to 1 for render GC to work correctly.  At this point, we really should see your render settings for verification and MR shader nodes.