Accuracy of Different Meters
Accuracy is a crucial factor when it comes to measuring instruments, especially in electrical engineering. Let's explore the accuracy of different types of meters listed in the question.

Moving Iron Meter
Moving iron meters are commonly used for measuring AC currents. They have a moderate level of accuracy but are not as accurate as some other types of meters. They are suitable for general measurement purposes but may not provide the highest level of precision.

Rectifier Meter
Rectifier meters are often used for measuring DC currents. They offer good accuracy but may not be as precise as other types of meters available. They are reliable for many applications but may not be the best choice when high accuracy is required.

PMMC Meter
Permanent Magnet Moving Coil (PMMC) meters are known for their high accuracy. They are often used in precision measurement applications where accuracy is paramount. PMMC meters are sensitive and provide reliable measurements, making them suitable for tasks that require precise readings.

Moving-coil Meter
Moving-coil meters are commonly used for measuring both AC and DC currents. They offer good accuracy and are suitable for a wide range of applications. While they may not provide the highest level of precision compared to PMMC meters, they are still a reliable choice for many measurement tasks.
In conclusion, among the meters listed, the Moving-coil meter has the highest accuracy. However, the choice of meter ultimately depends on the specific requirements of the measurement task at hand.