- Wordfence Security
- Pretty Links Lite
- Ninja Forms
- S3MediaVault WordPress Video Plugin and Audio Player For Amazon S3
- DigitalAccessPass (DAP) Membership Plugin for WordPress
- Yoast SEO
- Really Simple SSL (or SiteGround Optimizer)
- WP Super Cache (or SiteGround Optimizer)
- Smart Quiz Builder (for quizzes and surveys)
- Duplicator (backups and migrations)
See the full list at 27 “Must Have” WordPress Plugins For Your Business Website