Plugin development is an ever-changing field, and so is the best plugin for WordPress. The best plugin for WordPress today may not be the best plugin tomorrow.
That being said, there are a few plugins that are perennial favorites and remain essential for any WordPress site. These plugins include the Gravity Forms plugin and the Yoast SEO plugin.
For customizing and optimizing your WordPress site, the Jetpack plugin is a must. It includes features like site stats, security, and performance enhancements.
The bottom line is that there is no one “best” plugin for WordPress. What is essential for a particular site will vary, and what is the best plugin for one person may not be the best plugin for another.
Ultimately, it is up to you to decide what is the best plugin for your WordPress site.