The most commonly used CMSs are WordPress and Joomla for presentation sites / showcase sites

WordPress’s Woocommerce plugin or Prestashop CMS for building product catalogs or e-commerce.

The Drupal CMS for custom applications.

By far the most widely used CMS worldwide is the WordPress CMS, which by the way I prefer because in addition to being user-friendly for the end customer who wants to manage site updates themselves, it ranks very well on the Google search engine.