Our main flight computer is based around the Arduino Mega platform.  It is a very reliable platform and works well for logging telemetry and broadcasting positioning reports via APRS over amateur radio frequencies.  When purchasing any Arduino product, be sure the Arduino is genuine and not a fake, replica or counterfeit device.  Fake and replica Arduinos are generally not as reliable as they use cheaper parts, particularly when it comes to power regulation.  For details on how to check if your Arduino is genuine see this Arduino page.