Here are some popular UI libraries for React Native: NativeBase, React Native Paper, React Native Elements, and UI Kitten.

UI libraries provide a consistent look and feel across your app, which can enhance the user experience.

Pre-built components can significantly speed up development time.

Popular UI libraries often have strong community support, including documentation, tutorials, and forums where you can get help.

But I would argue that they are not essential!

Reasons to Consider Avoiding UI Libraries:

1. Learning Curve: Each library has its own components and APIs that require time to learn.

2. Customization Limitations: While UI libraries offer customization, there may be limitations that prevent you from achieving a specific design.

3. Performance Overhead: Some libraries can introduce unnecessary performance costs, especially if they include features you don’t need.

4. Dependency Management: Integrating a UI library adds another dependency to your project, which you’ll need to manage and update.

What Should You Do?

Focus on mastering React Native's built-in UI elements for more straightforward customization to meet your design goals. You can create your own reusable components—such as Buttons, Text, Toolbars, etc.—giving you full control over your app’s design.

If you choose to use UI libraries, consider abstracting their components within your application. For example, create your own button component that forwards props to the React Native Paper button. This approach makes it easier to switch or remove the library later on.

Happy coding!