While poutine is great, I think that's kinda cheating. The question was about forms of potatoes, not dishes with potatoes in them. "Cheese curds and gravy" is not a form of potato, and I doubt you'd rank the naked fries underneath so highly.
I do. Another tasty dish for sure, but the spirit of the question compels me to consider only the potato portion of the dish.
Now, I am content to control for toppings/seasonings. I would measure scalloped potatoes against cheese fries against a baked potato with cheese, etc. Or any potato variety covered in cheese curds and gravy.