Web Development

The answer to the original post is not whether one language should be preferred over another, but which development framework suits the requirements best. For the first, you could look into magento or zencart, also check Wikipedia (Comparison of shopping cart software - Wikipedia, the free encyclopedia).
You could benefit from this resource as well: Compare Content Management Systems - cmsmatrix.org - The Content Management Comparison Tool
Ultimately, you will probably use a combination of PHP and Javascript.

Most websites are built with PHP on the server side and JS as the browser side logic which is delivered by a PHP engine.

.. and since LAMP (Linux, Apache, MySQL and PHP) is by far the largest platform for delivering web applications, it should be obvious to anyone who develops web applications or administers a web site that PHP is the server side language of choice.

Check out CNN, the NYTimes, Wikipedia, etc etc. Most are written with at type of WordPress framework developed with PHP as the server side language and JS as the browser side language.

Also, my replies are not about "what language is best" .. I am discussing what is used the most across the Internet, and the biggest server/hosting side for for web application development is PHP based.

Go download WordPress (for example)... it is in PHP (server side) and JS (browser side), because this is the standard used by the largest communities on the web. Ditto for forums (written mostly in PHP for the back end).