WpSmush Pro is the fastest and most efficient image compression plugin for WordPress worth $588.
iThemes Security Pro
iThemes Security Pro is an industry wide used security plugin worth $80 which comes with 30 plus security features all included in a single package.
WpRocket is a premium WordPress performance plugin worth $39. It implements measures such as page speed optimization and caching to make your website blazing fast.
Akismet Spam Protection
Akismet is a spam protection service worth $60 which automatically filters out user generated data such as comments and contact form submissions.