I don’t think a person goes looking for WordPress plugins for the sake of having plugins. I think instead that they see a specific need and turn to plugins to accomplish that need. Often times there will be multiple plugins that accomplish the task. Which one gets quick, stable updates? Which one does it the best way? Most likely, if a plugin is popular, they are probably one to check out.
This infographic lists 30 top plugins by popularity.
(Credit: WPTemplate)