The question should be more like "Which of these excellent E-Commerce Shopping Cart plugins should I use?"
Both WP e-Commerce and WooCommerce are very flexible and scalable shopping cart systems that plug into the WordPress blog / content manager and immediately makes online shopping a breeze to setup. Just ensure that your web hosting service is up to date to handle the newest PHP coding.
Both plugins are free and include the standard functions worthy for any online store ready to sell anything and use PayPal for card processing. The standard shipping modules will do the necessary calculations but there are enhanced addons to make even more complex calculations as needed.
The advantage of using WordPress in combination with a shopping cart plugin is to benefit from the unlimited article posting ability, which will help to develop page depth and improve search engine optimization for top search results positioning. A function similar in Joomla.
Along with the benefit of unlimited article posting are numerous other plugins which supports all media options such as video gallery where you can post instructional videos related to your product or service and write valuable accompanying text that will draw in search bots.
A photo gallery plugin will display individual images of your product and also allows for descriptive text to again attract search bots and be listed.
Throughout the site, products will be displayed in 'sidebars' to keep the viewer aware of your items for sale. Specials, most sold, most viewed, highest rated or latest items are just some of the sidebar widgets which can persist globally and in any position desired. Using simple tags called 'shortcodes' allow for even more flexible widget display such as embedding within an article post.
All these plugins allow for page depth accumulation and really makes for dense keywords and phrases to make your WordPress shopping cart quickly visible to search engines and ultimately increase visitor traffic which may convert to sales.