Here’s a comprehensive list of React UI Libraries for your next complex non-trivial ReactJS project:

• Grommet (GitHub)
• PrimeReact (GitHub)
• ReactSuite (GitHub)
• OnsenUI (GitHub)
• React Bootstrap (GitHub)
• Ant Design (GitHub)
• Material UI (GitHub)
• Blueprint JS (GitHub)
• Semantic UI for React (GitHub)
• Evergreen (GitHub)
• Chakra UI (GitHub)
• Rebass (GitHub)