I was told once only people of faith will think that Gandalf is in fact a great wizard as they only ever tell you his is and you are expected to believe this even though you are never given any shred of evidence that he is anything more than an old man that can't die with a light shield and a police flashlight at the end of his staff. The idea that he is a great wizard is further hampered by the fact that in a great army battle where a proper wizard could decimate hoards of enemies with spells he chooses to melee 1v1.
Dumbledore all the way on thsi one.