Mightiest of the Maiar?

[Nikkolas]

Well I just found this....
"Sauron was as near an approach to the wholly evil will as is possible. Yet he had begun well, at least on the level of desiring to order all things according to his own wisdom. But he went further than any human tyrant in pride and lust for domination, being in origin an immortal spirit, of the same kind as Gandalf and Saruman but of a far higher order."

Seems to me Tolkien is saying here in no uncertain terms that Sauron as a being was innately much greater and more powerful than Curumo and Olorin.

So then was Sauron the strongest Maia? Or was perhaps someone like Melian even better?