Autodesk's AutoCAD rules the roost in many architectural firms and is almost universal among engineering consultants. The DWG format is the de facto standard for drawing exchange on almost all projects, and most institutional clients have also adopted it for their records.
With Autodesk now developing Revit, it is also becoming the BIM software most often encountered; I suspect it will ultimately be the standard in Canada (and the United States).
I've been using ArchiCAD since 1991 (release 4.0) and continue to do so, but our small firm merged into a larger, multi-office firm in January of this year and one result has been a gradual introduction to Revit which they are incorporating into the practice -- future work will be on that software (though I will maintain our database of ArchiCAD work that we have transferred and expand on it for repeat clients).
In my experience almost every other CAD software package is a "fringe" player in Canada except for VectorWorks, which maintains a reasonable market share. The firm we've merged into was an Arris-based office for over 10 years but got tired of constantly being out-of-sync with the Autodesk monopoly that exists and retired that software earlier this decade. They are not interested in repeating that experience and so have defaulted to AutoCAD (and Revit) as a result.
Not my first choice, but it's a common occurrence from what I've seen/heard.
Senior Associate, Chernoff Thompson Architects
ArchiCAD 16 (firm uses Revit)
Mac OS X 10.10 on Mac Pro (2013)
3.5 GHz 6-core Intel Xeon w/64 GB RAM & Dual AMD FirePro D700 w/6 GB Graphics
1 TB SSD w/20 TB RAID 1
Asus PB287Q 4k UHD 28-inch monitor (3840x2160)
