SK hasn't made an alarm panel in about 15+ years. -_-
As an aside, SK used to have what was called "firmware of the day" when I worked at Notifier and some of my coworkers would help out the SK support guys....SK seemed to push their panels/software through with all sorts of bugs, then need to be constantly patched.
Residentially, I typically install the Honeywell/Ademco Vista panels or the Elk panels. HAI is only really used when needed because of overall cost vs. features, as well as being a more "closed" platform for items like RF and tiered based on the panel vs. expandability and cost, where Elk has 2 panels that can expand (with some exceptions) to pretty much the same platform.
Pricewise, as a pro installer/dealer, once you start to load up a Ademco panel with expanders, etc. pricing becomes pretty close to an M1G with minor expansion, if any, but the functionality is night and day when you start factoring in the rules. Elk is very similar to the Ademco platform, modular and all their devices are compatible across their platforms, which are really the same panel, just slightly different hardware.
I can't justify using a HAI for a low end install because their platform is just too limited in the expandability and having 3 platforms, 2 that are hobbled out of the box for expansion unless you buy the Omnipro.
A M1G kit loaded up is half the cost of an OPII, though when you add the serials and ethernet to make them more apple to apple, the price difference isn't that great, the only difference I've run across is the memory space for logic equations/automation events.
In the end, the main difference between a "conventional" burg/fire system and a platform like the Elk and HAI is the flexibility of what you can do as far as controlling/interfacing to other systems and devices, which is easier on a "platform" than a conventional, which generally needs a lot more hardware and the end result isn't as integrated and slick.