ArchiCAD is -or at least aims to be- an all inclusive program for architects.

Ease of use, ease of learning, power, community, ease of integration

There are certainly many aspects that make Archicad a unique software, as far as I'm concerned the two fundamental aspects are the speed of management of extremely complex models, and above all the versatility, on this aspect I don't think there are comparable software on the market. Archicad allows great creativity in three-dimensional modeling, often allowing the achievement of the same result in a myriad of ways, becoming a real kind of Swiss army knife in the hands of an architect. Anorther important aspect is the stability of software, is really difficult to make Archicad crash, and honestly I've never lose the work I've done(and I use it from 1999, from my first year at university)