The northeast wins hands down when speaking purely of color variety and depth but David is also correct that the west prevails in majestic background enhancement. There are so many tree varieties in the northest that provide multiple colors and they come on very fast after the first killing frost. There are numerous types of Oak, Maple, Elm, Ash, Birch, Alder, Beech, Wild Cherry, Hickory, etc.----each with a different color scheme. What westerners call Aspen we call Poplar. There are probably suttle differences but I believe they are part of the same major species. In the east one will not find large forests of just Poplars. Usually, you just come across small groves of them because they have to compete with so many other species.
Jim