I second the Lake Fork, its one of my favorite rivers and recieves very little pressure. It has mostly rainbows and browns but there are brookies and cutthroat. Most of it is private but there's plenty of public access. Some of the private land owners stock it and feed the trout so there are some real hogs. When I used to float it we would catch a couple of rainbows over 8lbs each trip and the two biggest were over 10.