We would be taking your review on which you think is better to use React Native or Flutter but first let me sumarise what mobile mobile application development is and the types.
Application Development is the process of developing a mobile application for mobile device like ios/andriod. There are 3 type of mobile development which are Native, web and hybrid applications.

Native applications

what developers use

IOS -> swift or objective C
Android -> java
Windows phone ->Net

Mobile Web applications

Hybrid application

what developers use

Xamarin
Ionic
React native
Flutter

We want to talk on which is better for developers React or Flutter

1. React by Facebook is a js framework in which javascript is a very popular language among developers and it is really easy to install but they assume developers know how to set it up with no setup guide for Android projects, react native has more developer support since it started 2015 but with no great support for UI testing.
2. Flutter by Google uses dart which is not really popular among developers and most developers see it has stress learning it but it is very easy to use and understand , it takes longer time installing but offers more documentation and support for configuration and set up , flutter doesn't have much developer support since it started 2017 but with time it would, they have great support for UI testing.

According to what I think I believe using react is better because all developers uses javascript for development it easier to learn and use react Native cause it's not really different from React.

Review image by samaj