When evaluating EMF meters, prioritize the frequency range (measured in Hz, kHz, or GHz) to ensure it covers the specific sources you intend to monitor, such as 5G networks, Wi-Fi routers, or power lines. Look for devices that offer tri-axis (X, Y, Z) sensors for more accurate, non-directional readings. Additionally, ensure the device provides measurements for all three fields: Electric Field (V/m), Magnetic Field (mG or µT), and Radio Frequency (mW/m² or V/m). High-quality units should feature a sampling rate of at least 0.5 seconds and a backlit LCD display for clear data visualization in various lighting conditions.