Draw.io is a free, web-based tool ideal for quick diagramming and collaboration, while OmniGraffle is a powerful, professional tool suited for complex diagrams and graphic design, but it comes with a price and is limited to Mac users.
draw.io
Pros:
Free to use
Web-based and easy to access
Supports real-time collaboration
Wide range of templates and shapes
Integrates with Google Drive and other services
Strong community support
Regular updates and improvements
User-friendly interface
Customizable features
Good export options
Cons:
Limited advanced features compared to OmniGraffle
Dependent on internet connection for full functionality