Digest supports folders

Brief and Digest support folders. You can group feeds into folders, nest folders within other folders, and so on; you do this by arranging the live bookmarks in the same way as you would arrange any other bookmarks. Then you can left-click a folder to display all the entries in the feeds it contains, or right-click for other operations.

BTW, I did not know about Digest until I read this article. Thanks for that!