I like how Flutter is truly different. I learned just how different it is because it has a completely different problem, shader compilation jank. It shows what great risks the Flutter team took to create something innovative. It's paying off, and time will tell how big it will be! https://docs.flutter.dev/perf/shader
I think it really comes down to Google's level of commitment to Flutter. They've done a lot of great work so far and I think it could easily become the first choice for cross platform app development if they investing in it to the degree they have so far.
I'm not sure I'd use Flutter for the web yet but I definitely prefer it to React Native.