There are no hard and fast rules for what determines a good refresh rate for a monitor. It is dependent on your usage and varies accordingly. If you mainly use your monitor for casual usage, then, 60Hz would be fine. If you're using the monitor for VFX, animations, or high-rendering extensive tasks such as Motion Graphics and Hardcore Gaming, then, a refresh rate ranging from 120Hz to 240Hz would be sufficient. However, keep in mind that the higher the refresh rate, the safer and better for your eyes.