What map features are the most useful?

What map features are the most useful? When maping I would like to add the features that are actually useful and not just clutter. What sort of map features are important for a high quality map? I recently have been looking into adding stop sign and traffic light information. Are there any other map features that are usefull for a good map or are there any other features that could aid routing. What other use cases should mappers be aware of? Any advice is welcomed.