Reasons to Upgrade Your Website to Drupal 8

1. Future-proofing. At some point, all versions of Drupal will be designated as “unsupported.” Drupal 6 is now “end-of-life” and although Drupal 7 support is still strong, new features may not be added. Investing in a D8 upgrade now means getting the latest tech and saving budget resources in the longer run.
2. Easier upgrades. Moving to future versions of Drupal will be significantly easier if you upgrade to Drupal 8. In the past upgrades between major versions have been more complicated and time-consuming. The transition from D8 to D9 promises to be the easiest so far.
3. Drupal has moved its most crucial features and functionality to its core software, requiring fewer add-on modules to provide functionality. Therefore, there are fewer overall configurations required, making it a more streamlined platform out of the box.
4. D8 upgrades to contributed modules are largely in place, so you should have all the functionality that you require. Some modules may be in the process of being ported to D8. Check here for the status of D8 contributed modules that are critical to your business.
5. Responsive and mobile optimized--meaning that your desktop design will automatically adjust as required for smaller display screens. This saves the time it would require to design two interfaces.
6. Much-streamlined admin UI with vastly improved authoring experience. The organization and design of the UI have been overhauled and optimized for configuration management. For people who work on the website regularly, this is a pleasant upgrade. It provides an intuitive and simplified content authoring experience that is just cleaner and easier with in-context editing for speed and better content management.
7. New Twig Templating engine makes the theming experience simpler and more powerful with unprecedented flexibility.
8. Powerful multilingual capabilities for easy auto-translation of ANY content. Accessible across nearly 100 different languages, giving your website the potential for global reach.
9. Mobile-first ethos recognizes the rapid shifting of web content consumption from desktop to the small screen. Everything has been redesigned to make mobile a priority, including module page layout and the installer UI.
10. Media module is here in Drupal 8.5.0 At last, a long-awaited solution for managing image and media elements in Drupal will put it on par with CMS's like WordPress, which are lauded for ease-of-handling for media components like images and video. Media management in Drupal 8 can be done effectively right now without the Media module, but requires more configuration of multiple modules, as discussed here in a blog post by Adam Fuchs.
11. More Security built in by default. Security is always a top priority and Drupal 8 has made a great effort to beef up its already solid reputation as one of the most secure CMS's around. This video explains some of the improvements in this area.
12. Performance optimizations abound with Drupal 8. For example, speed improvements with improved caching will lead to knock-on benefits for better visitor engagement and higher quality SEO.
13. Drupal 8 is a true technology integration platform with the API's to connect a huge variety of other tech to make your organization more competitive. Whether it's marketing automation, database integration, sales and project management software or other specialist tech solutions, chances are that there is a path to integration.

There are numerous other enhancements to this release (some highly technical) that are not mentioned here, and new features are being tested and rolled out even with point upgrades. These are exciting times for Drupal.

For more granular insight on all Drupal 8 changes as they are rolled out, consult the change records for Drupal core