My area has a decent mixture, but it’s not hard to discern the prevalence once you start looking. Listed below from most to least prevalent:
Siemens//Cerberus Pyrotronics//Pyrotronics//Pyr-A-Larm
Fairly common already and growing in popularity as of late. Pyrotronics and Simplex both developed a great customer base here from the 1960s onward, but the former has seriously surpassed Simplex in the past few years. Three of our school districts now use Siemens exclusively in new installs and retrofits; my district even did a mass replacement last year that saw every Honeywell and EST system ripped out and replaced by a new Siemens system of either the Cerberus PRO or FireFinder XLS varieties. New, smaller Siemens systems seem to be cropping up in commercial establishments around here more and more frequently, especially the Cerberus PRO FC901 and FC922 panels. Some of these have replaced Honeywell, EST, and even a couple of old Autocall systems. Of course, the Z-Series line has become even more ubiquitous than the SpectrAlert Advance around here, though some of the new systems use Siemens NS-MC-CR’s (Wheelock NS-24MCC-FR) for ceiling notification. Initiation devices are H-Series detectors and the HMS-D pull station in particular seems to be the favorite pull. The older Siemens ans Cerberus Pyrotronics stuff uses basically everything they’ve offered over the years for both notification and initiation.
Simplex
Fairly common, but slowly losing ground in the smaller segment. Most of the systems installed around here in the past decade have been of the large 4100U/4100ES variety. Most of the middle and high schools in a neighboring school district (all with 1000+ students) have these systems with either Simplex TrueAlert (4906 variants) or Wheelock NS/RSS signals. One middle school has a red 4100U with white ZNS horn/strobes (wall and ceiling) and white ZRS (wall and ceiling) strobes. Older systems are mostly 4020s, 4002s and 4005s, some replacing 2001s and 4207/8 panels. There are a few 4010s, but most of the older 4100 systems have been upgraded in the past five years to 4100ES equipment. Initiation devices are pretty much your standard 4098/4099 fare. Most of the older systems use 4903-Series, 2901-9833+2903-9X01, or 2901-9838+4903-9101 signals and pretty much your run-of-the-mill Simplex initiating device fare. Anything older than this has pretty much been totally upgraded by now.
Honeywell: Fire-Lite//Notifier//Silent Knight//Gamewell-FCi
Common, but losing ground to Siemens. Fire-Lite and Silent Knight are by far the most common of the four, especially the MS-9200 series and the older IntelliKnight series panels. Notifier and Gamewell-FCi aren’t too hard to find, the former mostly using NFS2-640 or -3030 panels in large installations and the latter using the 7100 or GF510 panels for smaller systems. As of the past two or three years, an increasing number of these systems have been replaced by Siemens systems as the integrity of the installation quality has been questionable at best, especially on the Silent Knight end of things. Signals post-2008 are usually the oh-so-common and oh-so-adored SpectrAlert Advance line, occassionally the Gentex Commander line, and initiation devices are the usual BG-12/System Sensor fare. Pre-2008 is a mixture of Wheelock AS/MT/NS/RSS/ZNS/7002T, System Sensor SpectrAlert Classics, System Sensor MASSes, and the occasional Gentex SHG/GMS/GXS signals. Initiation devices are either BG-10s, BG-8s, Century’s, MS-2’s/MS-6’s/PS-SATK’s and older System Sensor sensors.
EST//Edwards//AIP
EST and Edwards are somewhat common in 1980s-1990s-early 2000s buildings around here, but the oldest systems and all the QuickStarts are starting to go, usually replaced by Siemens or occasionally Fire-Lite. Especially common panels in this category are the EST3 and the Edwards 2400/EST1. A few small, late-80s locations around here have or had AIP systems, but at least three of those have been replaced (one by a Fire-Lite MS-5UD, one by a Siemens SXL-EX and the last by a Siemens Cerberus PRO FC901). Newer systems are the usual SIGA- and Genesis fare, but the older systems are a mixture of Integrity, 892, 792 and Adaptahorn signals and 270-SPO and Edwards/System Sensor detectors.
Autocall
Exactly three establishments in this area have/had older Autocall systems. I can’t say what the panels are/were, but the alarms in all three systems are/were Federal Signal 450D+VALS signals and 4050-001 pull stations. One system had a 450D+V1971 ADA-compliant horn/strobe. One of these three systems, in a local grocery store, is currently in the process of being replaced by a new Siemens Cerberus PRO FC901 system as I type. The Autocall system is still in place, but new Siemens NS-MC-CR/ZH-MC-R/ZR-MC-CR signals, OP921 smokes and HMS-D pulls are being installed as I type. There’s also a new Siemens FSD901-R3 annunciator at the front of the store.
Any brand not mentioned above doesn’t have enough of a presence in my area to be included. I know of at least one Mircom and Hochiki as well as one National Time system, but they’re strictly outliers.