"But at length the Shadow returned and its power increased; and in that time was first made the Council of the Wise that is called the White Council, adn therein were Elrond and Galadriel and Cirdan, and other lords of the eldar, and with them were Mithrandir and Curunir. And Curunir (that was Saruman the White) was chosen to be their chief, for he had most studied the devices of Sauron of old. Galadriel indeed had wished that Mithrandir should be the head of the Council, and Saruman begrudged them that, for his pride and desire of mastery was grown great; but Mithrandir refused the office, since he would have no ties and no allegiance, save to those who sent him, and he would abide in no place nor be subject to any summons."

I think that Saruman was perhaps more clever or intelligent but that Gandalf was self-confident and wise. Sarumans own ambitions (among them mastery over others) lead him to his own downfall while Gandalfs stoicism and desire for free will lead to his victory. Reminds me a bit of Tom Bombadil... it seems that Tolkien put great measure into people who chose to live their lives as they see fit without encroaching on others.

M