The deprecation of the `execCommand` function has indeed led many developers to reevaluate their approaches to implementing rich text formatting in web applications. While the Selection and Range APIs are powerful tools, they come with a steeper learning curve compared to the simplicity of `execCommand`. These APIs allow for fine-grained control over the selection and manipulation of DOM elements, which means you can achieve a similar level of formatting. However, due to their complexity, it might be beneficial to leverage reliable libraries such as Quill or Slate.js. These libraries encapsulate much of the complexity involved in building a rich text editor and provide a user-friendly interface that can help you maintain a consistent user experience across different browsers, relieving some of the burdens associated with manual implementation and browser compatibility issues.

If you decide to pursue a custom solution, I would recommend starting with a solid understanding of the Selection and Range APIs, alongside an exploration of modern JavaScript frameworks that can assist with state management, such as React or Vue.js. This combination can help you build a robust foundation for your rich text editor. As for browser compatibility, always check the documentation for any new APIs you plan to utilize, and consider implementing feature detection as a safeguard. Tools like Babel can also help you use modern JavaScript syntax while ensuring compatibility with older browsers. Overall, focus on modularizing your code and creating reusable components, which can significantly simplify your development process and enhance maintainability. Keep in mind that the community is full of resources, including articles, tutorials, and documentation, so connecting with others who have gone down this path can prove invaluable in navigating this transition.