* Meters per second (m/s): This is the standard unit of speed in the International System of Units (SI).

* Kilometers per hour (km/h): Commonly used for road vehicles and other land-based transportation.

* Miles per hour (mph): Used in the United States and some other countries for road vehicles.

* Knots (kt): Used for maritime and aviation speed, where one knot is equal to one nautical mile per hour.

* Feet per second (ft/s): Used in some engineering applications.

The best unit to use depends on the context of the measurement.