Some of the best waterfalls I have seen are in Oregon.
But I do like falls in Arkansas. Gloryhole Falls is the best and most unique small waterfall that I have ever seen.
Below is a picture of falls in Oregon. We think less than 30 people have ever seen these falls. Our guide discovered this about 5 years ago and he has taken 30 people or so to see them. He is normally in Utah, but does Oregon 1 or 2 weeks each year. I was suprised that you didn't have Tunnel Falls, and Punchbowl Falls in your top 10 list for the US.