There are several excellent multi-user, online project management tools available, each with its own unique features and benefits. The best tool for you will depend on your specific needs and preferences. Here are three popular options:

1. Asana: Asana is a widely used project management tool that offers a user-friendly interface and robust collaboration features. It allows teams to create projects, assign tasks, set deadlines, and track progress. Asana offers various views, such as list, board, and timeline, to suit different project management styles. It also integrates with other popular tools like Slack, Google Drive, and Dropbox, enhancing collaboration and productivity. Asana's free version provides basic functionality, while the premium version offers advanced features like custom fields, dependencies, and advanced reporting.

Reference: Asana website - https://asana.com/

2. Trello: Trello is a visually appealing project management tool that uses a card-based system to organize tasks and projects. It provides a simple and intuitive interface where users can create boards, lists, and cards to represent tasks and their progress. Trello's strength lies in its ability to provide a clear overview of project status and encourage collaboration within teams. It offers features like due dates, checklists, attachments, and comments. Trello integrates with various third-party apps like Slack, Google Drive, and Jira, providing seamless workflow integration.

Reference: Trello website - https://trello.com/

3. Monday.com: Monday.com is a versatile project management tool that offers a highly customizable and visually appealing interface. It allows teams to create boards, track tasks, and visualize project progress using different views like Kanban, Gantt charts, and timelines. Monday.com offers various templates that cater to different industries and project types. It includes features like task dependencies, time tracking, integrations with popular tools like Slack and Google Calendar, and advanced reporting capabilities. Monday.com offers different pricing plans based on team size and requirements.

Reference: Monday.com website - https://monday.com/

It's important to note that the "best" tool ultimately depends on your specific needs, team size, budget, and preferred features. It's recommended to try out free trials or demos of these tools to see which one aligns best with your requirements before making a decision.