What has proven to be the most beneficial feature of project and task management tools?

I actually agree with @jana_simeonovska who've highlighted visibility and transparency. But I'd say deadline management is also one of the most important features of management tools. From my own experience, placing tasks and events on a visually appealing timeline where you can easily set and track deadlines is an extremely useful option. This feature is presented differently in different tools. When I worked with MS Project, something was missing. But when I discovered a great alternative to Microsoft Project (https://blog.ganttpro.com/en/mic...) GanttPRO, work with timelines and deadlines became more smooth and clear.