I don‘t have practical experience with flutter but between ionic and react native I‘d say both a perfectly viable options and we have used both for a number of production apps. We normally go with ionic on capacitor because we build a lot of pwa/web apps so we can use the same code for all. We don‘t use much of ionic elements, we do most styles on our own.
The comments that the user experience is bad I cannot agree with. A well designed and developed ionic apo can hardly be distinguished from a native app. But obviously that depends also on the usecase and type of app.
I hope this helps