Since there had been no answer to this question, I'll provide this info for the future reference of others.
Since 1996 there has been only one dedicated CAD and SolidWorks -> Cinema-4D conversion system. You would never use STL since that is the world's worst 3D file format. You would also not want to use OBJ because (1) it will not retain the CAD assembly hierarchy and (2) Cinema-4D's free importers do not allow for the all-important and accurate CAD normals to be imported.
For reference of those who do need a 1:1 and proper conversion: