I mostly do 3D Coat to create the first concept art since no drawing and voxel gives me great for this task. I then use ZBrush and Maya to improve and see the light better model or prototype of my project. In some cases like the panther phenix 52, I again use 3D Coat and highly technical tools such as curves, which were used for the entire spine and tail of the model. If the model is organic use the Retopo room and I do once the UV. If is the hard surface do the UV in Maya.
Best Regards.