Since both DVD and BD have a fixed frame size, "cropping" away won't result in any standard DVD/BD if we stick to the definition in the dictionary. If you want compatibility you have to stay with 720 (or 704)x480 and 1920x1080.
The best does not exist here and it depends anyway on what you want to do. Cropping away is not only not the best but it is also illegal
by the book.