I'm using Foldersync for a while too as well, linked it to my OneDrive.
I only use it for photos, but what makes Foldersync superior to the official apps is that it lets you specify which folders get backed up, and what folders they backup to. So instead of the normal put all the photos in one folder backup solution of most clouds (or put them in folders per date), I recreated the albums in my OneDrive. So the screenshots album go to a folder called screenshots, the wallpapers album to a wallpaper folder, and so forth.