My favorite fire alarm panel company is…
There are numerous fire alarm panels from many different companies. What company makes your favorite fire alarm panel?
(any companies I’m missing?)
It’s Johnson Controls, not Johnston Controls, just so you know. 8)
My favorite out of all of those companies is probably Simplex.
Oh, and you’re missing Faraday and Cerberus Pyrotronics.
MOD EDIT:
Removed the options “Your Homemade Panel” and “AlerteK” because “homemade” does not count and even though I appreciate the reference to me, Alertek is not a real company and therefore I did not include it on the list.
Also, I fixed the spelling error on “Johnson”.
Johnson Controls’s current fire alarm panels are all actually Notifier panels that JC rebrands.
Cerberus Pyrotronics and Siemens are the same though; it should say “Siemens/Cerberus Pyrotronics”
#1 - Simplex
#2 - Siemens
I couldn’t decide on a #3, the rest are all the same to me. 
Hmm. I’d add all those in but I can’t seem to edit my post.
Added more options:
Faraday and Cerberus Pyrotronics are separate from Siemens, because while being owned by Siemens now, they once had their own panels. I left those options in in case someone prefers older Cerberus panels over newer Siemens ones.
Added a few more brands that were missed.
1st: Thorn/Autocall
2nd: FCI
3rd: Simplex
To answer the question the topic name is asking, Simplex (because that was my first fire alarm system I have heard ever), with Faraday and Siemens coming in second (because of the now-defunct U-HNHs.)