There are many different styles, shapes, sizes, and descriptions of hanging signs that are perfect for any occasion or business.  The proper banner depends on what it will be advertising or disclosing.  Some shapes are more important than others, while size may matter depending on the distance from which the advertisement must be read.

Some hanging signs are better if they are longer than they are wide, and they are displayed in this fashion.  This makes them a little different from the standard type that most businesses use, and therefore, it would make the advertisement more noticeable.  The whole objective is to get the attention of those who pass by, and one that is vertical instead of square or horizontal is definitely unique.  
Some businesses are known for one type of goods or products.  For this reason, they sometimes opt to have hanging signs in front of their business that are in the shape of this type of product.  An example would be a fruit stand that wanted an advertisement in front of the store.  They may wish to opt for an advertising banner that is in the shape of a banana or grapes.  This would make the banner stand out and would make it eye catching.  Another example might be a bicycle shop that had a banner in the shape of a bicycle.  This would tell the passer by what was being offered in the shop even without reading the lettering on the banner.

There is also the option of displaying hanging signs with a motor that causes it to turn periodically.  This again is an attempt to set it apart from the rest and to attract the attention of the potential customers as they pass by the store.  The motorized unit would be easy to install and then attach the banner to so that it could constantly move.  This would be noticeable in a sea of banners that are attached to other storefronts or those that are stationary.  

Hanging signs are just easier to read and attract more attention than those that are affixed to the front of a building or storefront.  They give a depth to the message that isn’t found by those that are less noticeable.
 
Anyone who has ever tried to read the front of a store in traffic while driving can testify that this is not easily done.  However, the type of banners that are displayed independently and out away from the building are much easier to take in at a glance which is usually the amount of time that a driver has to take in the information while passing by.  Also, these types of banners are usually easily read through the windshield of a car which is the target that most businesses should be trying to hit when erecting a banner that will be in place where there is heavy traffic.  On the sidewalk, a banner that is displayed in this way is also much easier to see and find than having one on the storefront.