Choose Ionic if You are working on an application that is built on Ionic. You are going to develop a progressive web application. There is a need to leverage web development capabilities to provide web and mobile experiences. You have a considerable web development experience and will be developing an application for a startup business.
For Progressive Web Apps Enterprise-Level Apps Hybrid Apps and Mission-Critical Apps Ionic is the best choice. Your development team has no experience with native apps but has experience with HTML CSS and JavaScript. You need to develop an application mobile app development service in a short time and don't need high performance. You don't need native mobile features.
There is a need to keep a single code base between the website and the mobile. It is impossible to make a definite statement about which framework is the best Ionic or React Native. If you require lower development costs a faster development process and ease of building an application Ionic is the best option.