Is there any preferred measuring unit in writing? Since a few countries refuse to drop the imperial system, I am not sure if I should go imperial, metric, or just measure every distance as a number of cows.
You should use whatever unit your POV character would use. Or, if omni POV, then the standard unit for that time and place. A middle-aged British character would think in yards rather than metres, but a British teenager would think in metres. A Brit would think of a person's weight in stone and pounds, whereas an American character would just use pounds.
