Microsoft Visio vs OmniGraffle

Microsoft Visio
Create professional diagrams to simplify complex information with updated shapes, collaboration tools and data-linked diagrams. Simplify complex information with professional diagrams you can create in just a few clicks. Visio makes diagramming simple - whether you want to quickly capture a flowchart that you brainstormed on a whiteboard, map an IT network, build an organizational chart, document a business process, or draw a floor plan. Microsoft Visio free cloud alternatives are: Gliffy, Google Drawings, Creatly, DrawAnywhere, Diagramly
OmniGraffle can help you make eye-popping graphic documents—quickly—by providing powerful styling tools, keeping lines connected to shapes even when they’re moved, and magically organizing diagrams with just one click. Create flow charts, diagrams, UI and UX interactions, and more. Whether you need a quick sketch or an epic technical figure, OmniGraffle and OmniGraffle Pro keep it gorgeously understandable.
Face to face in the news:

2018 - Microsoft Visio integrates with Hololense. Beware OmniGraffle !

Microsoft is putting its AR headset Hololense forward as a way to increase productivity, quality, and safety by helping companies reimagine processes, data, and people to accelerate business impact and create value for customers. In particular, Microsoft Visio has been updated to address intelligent manufacturing scenarios, including facility layout. Microsoft will be showcasing Intelligent Manufacturing scenarios supported by Microsoft customer Dürr AG and incorporating Microsoft Visio Partners FaciWare GmbH (facility management solutions) and X-Visual Technologies GmbH (PnID solutions). So we may assume that Microsoft Visio gets more innovative in comparison to OmniGraffle

2008 - OmniGraffle 5 adds support for Microsoft Visio files

The new version OmniGraffle 5 is remarkably powerful and flexible, and is a worthy refinement to an already mature product. The Pro version picks up some high-end capabilities, such as greater support for Microsoft Visio files, custom data tables for each object, sub-graphs for taming very large documents, automatic document scaling, ColorSync support, and a simple presentation mode. Upon launching OmniGraffle Pro, you’re presented with the option of creating a new document from a range of templates. The generally simple and utilitarian templates are grouped by type: Drawing, Brainstorming, Organizational Chart, Space Planning, and Miscellaneous. OmniGraffle Pro also writes to Visio XML, making it capable of round-trip sharing with users of Visio—a Windows-only product. All the formats I tested turned out sharp, accurate versions of the original.