For an application, its either Angular, or React.
I know the problem. But this is not a question about Ionic, it is if you think Angular or React is better.
The most important thing is that the framework is supported a long time and not replaced by a newer one in a few years. For this, both frameworks have done quite well the last view years, probably because both have huge companies behind them (Angular - Google, React - Facebook).
It’s like deciding between Java and C#.
Both have advantages and disadvantages, but you have to decide for yourself with the knowledge what exactly you need.