Assuming that electrical conductivity is your primary concern, rGO is clearly more conductive. What you lose with rGO is water solubility (stability). The normal approach is to use GO to form the morphology you're looking for, then reduce it to rGO either chemically or thermally to improve the electrical properties. There are approaches now that may allow you to use pristine graphene rather than either rGO or GO, however. 

For supercapacitor, GO will be better material as it exhibits much higher specific capacitance than rGO. 

Like Mr. Douglas said it depends upon your purpose. If u want to Improve electrical conductivity go for rGO, if u want to enhance pseudo capacitive or redox nature go for GO.An exfoliated GO will be much more useful.

Graphene oxide would be better material than rGO for supercapacitors since GO has high specific capacitance.

GO is preferable to RGO as electrode materials for supercapacitor application. RGO has lost most of its oxygen-containing functional groups. The epoxide group, most expecially enhances the electrochemical properties of GO.