The Pixpro AZ421 has a CCD sensor type which is better than most cameras of a comparable age and type to it. Most comparable spec digital cameras that have been around for a similar time to it have a MOS sensor type. CCD sensors produce high quality, low-noise images but consume a lot more power than CMOS sensors. CCD is the most common image sensor type used in digital cameras.
This camera's sensor type (CCD) is in fact the best sensor type amongst all comparable spec digital cameras that are a similar age to the Pixpro AZ421.
Amongst similar types of camera the worst sensor type is MOS.