The title is actually very different than what the poll presents, seeing how favorite =\= best. I could like Lion Form (which isn't really a drive, either, but meh...) the most but would still think that Final Form's the best.
Also, Halloween/Christmas town forms don't count. Sora can use drives while in those "forms"
Then we have the issue of not even fighting in Atlantica.
Lion and, er, Dice are sort of ok since they change Sora's abilities, but... who'd vote for Dice? o-o;;;
Should've also included Card form.
As for best Drive Form, that really depends on what enemy I'm fighting. As a general rule I'd have to say Wisdow; it saved my rear end during a lot of fights where even Final Form failed me, due to Final Form being half the time a close-range battle form and against Tiffa, that gave me hell x.x;;;
As for favorite... iono. They're all cool in their own way X3