For smaller to mid-sized buildings in my area of the city, EST QuickStarts (especially with Genesis signals) and Mircom FA-1000s are pretty common while bigger buildings and high-rises tend to have EST3, 4100(U/ES) and MXL/XLS systems.
The variety within the city, however, is enormous: Gamewell, Grinnell (rebranded Mircom panels), Standard Electric Time, Fire-Lite/Notifier/Honeywell, Electro Vox and Mirtone (and probably others that I forgot) systems can all be seen.