Choosing the right metric for performance monitoring is crucial to ensure accurate insights and effective optimization. Averages provide a simple overview of overall performance but can be misleading when data is not uniform. Percentiles offer a more nuanced view by dividing data into segments based on their distribution, revealing how well the system is performing across different scenarios. The choice between averages and percentiles depends on the application's variability, user experience perspective, and monitoring objectives. By selecting the right metric and interpreting its results correctly, developers can gain a comprehensive understanding of their system's performance, leading to improved user satisfaction, faster issue resolution, and better scalability planning.