1.4:3 for office use,for schools and educational purpose since we will always using PPT in meeting,4:3 will help you make the image contain more content.
2.16:9 as per you use at home for home theaters,we are using projectors for videos,most of the videos are in 1080P HD,so this format will help projector getting the image with black border and playing full HD videos.
3.16:10 less uses
4.1:1 to getting videos from some countries,and they are more use as a widow shade and as projector screens