Act as a senior React developer with 5+ years of experience in building scalable applications. Explain the key differences between useReducer and useState in React, focusing on when to use each. Provide a detailed comparison of their use cases, performance implications, and readability. Include examples of [specific scenarios] where useReducer is more suitable than useState, such as managing [complex state logic] or handling [multiple state transitions]. Also, discuss how useState can be more straightforward for [simple state management] and why it might be preferred in those cases. Conclude with best practices for choosing between the two based on the complexity of the component and the scalability of the application.