Drive up and down the Icefields Parkway in Alberta or on Going-to-the-Sun Road in Glacier National Park and you'll see a lot of contenders.
Personal lists are always interesting because they reveal people's particular interests, but these generalized lists strike me as pretty silly. I think sometimes "most photographed" or "most visited" becomes mistaken for "most beautiful."
Two personal favorites of mine, and only a relative handful could name them without looking at the captions that go with the pictures:
And this one (on the left), which will be recognizable to more than a few:
They won't make any of these published lists, but my pulse races every time I see them.