OmniGraffle is
the OG. As in it's been around from the start. I remember having a license for it more than a decade ago.
The Omni Group were making software for NEXTSTEP/OpenStep and were among the first companies to publish real,
usable software on Mac OS X close to its 1.0 launch in 2001.
They may charge a premium, but it's because they're putting out quality software. They've stayed on top of the evolution of NeXT to Mac OS X to macOS and iOS and such, and their software has always been trying to do interesting and innovative things. I remember early versions made heavy use of drawers. Drawers! Remember those stupid Mac OS X things??
