Who do you think would be a good 'second' choice to bear the ring to Mordor.

[Thorongil]

Gandalf was offered the Ring, but if he had it, instead of a Dark Lord, the world would be subjected to extreme goodness everywhere.

This ring is pure evil. It could not have been used for good.Gandalf says so himself in the movie:

But through me, it would wield a power too great and terrible to imagine .