HardyPress - Use Wordpress as a static site generator
WP Rocket - WP Rocket offers a caching plugin for Wordpress.
SocialWeaver - Social media listening, engagement, & publishing all-in-one
Yoast - Yoast offers plugins to improve SEO and optimize web sites and blogs.
Postcron - the easiest way to schedule posts. Auto post on Facebook Pages, Facebook Groups, Facebook Events, Twitter, Linkedin, Google+, Pinterest & Instagram all from one place.
Wordfence - Comprehensive security plugin for WordPress.