WordPress is the simplest yet most durable Platform to use to build a Website.   You can Optimize it for SEO, Custom Build it, Many Templates, WYSIWYG Editors (What You See Is What You Get Design).

As of June 2017 WordPress is the most popular CMS (Content Mangement System) with a usage of 28.3%, Market Share of 59.4% dominating Joomla, Drupal, Magneto, Blogger.   Source w3techs.com

Maintenance can be tedious that is why it is important that you have a working relationship with the web design firm.   Minimize Custom Code and work with a business that offers you a Monthly Maintenance Plan.  

E-Commerce is easy to run, with the Woo Commerce Plugin.  In my opinion, it is better to go with Woo Commerce unless you are willing to spend more than a  Sunbstantial amount per month on an Enterprise Solution.  

WordPress is amazing due to having so many Out of the Box Solutions.  Rather than paying a coder to develop a specific solution then disappear.    Plugins Solve this issues with 51,022 avaliable Plugins.   The trick is knowing which one you need.

Being the most Popular CMS on the internet makes it the biggest target for hackers. We have a Layered Security Strategy which can literally Block Countries and IP’s

The Ability to Grow your site and create Pages without calling your Developer is crucially important in our current environment.   All Websites should be built to GROW.  WordPress allows this due to its easy to use Backend.

Your Website needs to be attractive and functional on Mobile.  Most people today use Mobile 1st and Desktops/Laptops 2nd.  Making a site easy to use on Mobile is Crucially important.   WordPress allows this with Responsive Designs.

Depending on your Budget you can make a Mobile APP for Andriod and IOS.  The content can be pulled from your WordPress Site with Ecommerce Capabilities.

For the reasons provided here, I prefer WordPress.  For specific Niches I have other solutions I would go to, for Webdesign, E-Commerce, and Mobile I recommend WordPress.