What have you done for me lately? Well actually we dont know what Graham has been doing in Zion but we do know that the courier has been out bringing down entire armies almost single handedly. Seems like when this whole thing is over with the courier is going to be quiet a legend himself.
Exactly, Graham might have some rep when it comes to the Legion but hell, The courier defied DEATH.. Getting shot twice in the head at point blank range > Getting lit of fire and pushed down a hill.
Grahame fumbled a huge battle, badly. We, the courier single handedly reroute power from a major installation, (twice if you steal the helios power for the thumb of god weapon) destroy the fiends, destroy the BoS, Make supremely powerfull allies (Boomers)
AND, at the end of the day drive out two post apocalyptic super-powers, on your own!
Courier > Graham WITHOUT A DOUBT.