Buyers should prioritize the Sensor Type (Optical, Capacitive, or Ultrasonic). Capacitive sensors are generally preferred for high-security mobile devices due to their ability to detect live tissue, while Optical sensors are cost-effective for time attendance systems. Key metrics include Resolution (typically 500 DPI), False Acceptance Rate (FAR < 0.001%), and False Rejection Rate (FRR < 0.1%). Additionally, verify the Storage Capacity (number of templates) and Interface Type (UART, USB, or SPI) to ensure compatibility with your controller.