- Flutter widgets can be made pixel perfect replicas of native UI components.

- Supporting older platforms is much easier with Flutter.

- You can use native UI components with Flutter if you want to, and mix them with Flutter widgets.

- Flutter has a tiny and fast runtime, React Native runs on Safari or Chrome. Flutter works great on embedded platforms too, such as IoT devices.

- Dart is similar to JavaScript, with the same runtime behavior, though obviously you can't use existing JavaScript libraries outside of the browser. You can use many WASM ones though.