GEES is an all-in-one AI design platform that is shaping a future where different design modes can seamlessly switch within the same file. In GEES (beta version), the whiteboard mode and UI design mode have already been launched, while the prototype design and graphic design modes will be launched in the near future. With AI assistance integrated into each design mode, GEES empowers users to enhance their design workflows effectively. GEES believes that such a new all-in-one era can make everyone enjoy a better design and collaboration experience. Whether you're a UI/UX designer, graphic designer, product manager, developer, or marketing manager, all your work can be unified in one file.
Based on our record, Lightning Design System seems to be more popular. It has been mentiond 2 times since March 2021. We are tracking product recommendations and mentions on various public social media platforms and blogs. They can help you identify which product is more popular and what people think of it.
LWC is supposed to be their approach to play nice with web standards and appeal to a broader group, and "web components" without the lightning niche specific stuff can get you close especially if you use https://lightningdesignsystem.com for your off-platform-hosted page and web components. Source: about 1 year ago
This is a bit more of a broad topic than your original question but the lightningdesignsystem.com website is always a good resource for various specifics on styling and SLDS (aura). Source: over 2 years ago
Ant Design - An enterprise-class UI design language and React implementation with a set of high-quality React components, one of best React UI library for enterprises
Sketch - Professional digital design for Mac.
Material UI - A CSS Framework and a Set of React Components that Implement Google's Material Design
Figma - Team-based interface design, Figma lets you collaborate on designs in real time.
Atlaskit - Atlassian's official UI library for React
FigJam - An online whiteboard from Figma designed for teams