Although Yoho National Park is the smallest among these national parks, it has my favorite, Moraine Lake, which ranks number one. The road may be closed in early October in winter, so you can't go in.
Yoho National Park in the Canadian Rockies is the smallest national park in the region, but it is "small and exquisite" and is famous for its magnificent scenery. "Natural Bridge", Bow River, waterfalls in the pictures below...