The debate between Flutter and Ionic centers on their distinct advantages and drawbacks for mobile app development. Flutter offers high performance with a single codebase and beautiful, customizable UIs. It's ideal for complex applications but has a steeper learning curve. Ionic, on the other hand, leverages web technologies, making it easier for web developers to create apps. It excels in rapid development and access to native features, but performance can lag in more demanding applications. Ultimately, the choice depends on your project requirements—Flutter shines in performance and design, while Ionic is great for quick deployment and web integration.