Sorry for those who think ALPS are all the same, they are far from it. I have some that are barely typable and others that make Topres and Cherry reds fall to their knees and reevaluate their own existence.
In my experience the best are early Blue and White complicates and some Fukkas if the caps and board are right. Not all Blues are perfect and only some whites are. The cutoff year is said to be around 1992 but I have two late 80's boards where one has the sweet ALPS and one doesn't. I believe the difference comes from the shape, angle, length of the two tangs on the click leaf. There are other factors but they seem to be the most significant and affects the tactile bump and feel of the switches more than any other (assuming they are clean)
The leaf on the left has the right tangs on it (I don't know what to call them) the one on the right is the more common early complicated leaf that is nice but not in the same realm as those on the left.
As for Northgates, No keyboard ever made had so many features. They were the only PC manufacturing company that chose it's keyboard as it's standout means to differentiate itself from the others. Northgate made the best keyboard out there and for some years it was the #1 selling keyboard in the US.
Not only is the scan rate fast, it's programmable! (some versions) and you can store it in the flash onboard. You can program scan and repeat rates, key mappings and other changes into the keyboard's hardware so when you unplug it to carry to work or get a new PC, none of your settings are lost. The backplates of Northgates could be used as tank armor. Detachable cords. Doubleshot key caps. Control key where it should be, but is swappable with capslock if you wish. They came with dust covers and key pullers and spare key caps for swaps and Dvorak in some cases. The only keyboard that ever approaches their build quality are early IBMs, but they did less "stuff".
This early 90's Northgate Ultra Plus was saved from a recycle heap. It is a no-trapdoor 8 dip switch model that has the omnikey cluster, PS2 AND ADB on the back and is compatible with Amiga. It has it's own reset button too. These aren't blues, they are whites but I've never felt ALPS superior to this keyboard. But I have tried other similar boards that felt different.
This 1988 Metal Gold Label 102 has Blue ALPS
The only issues with Northgates are that they tend to yellow with age and if ALPS are dirty or abused they don't feel as good as a cherry or buckling spring board that is dirty or abused. Handy that a dust cover comes with the keyboard.
Say what you will about Northgate Bob but this is how keyboards arrive from him and he takes returns if you are unsatisfied. I got an Ultra Plus from him that was a real banana once I got it and he offered to take it back but I kept it.
To the OP, the dampened ALPS in SGI's and Apple AEKII's are wonderful switches if you get good clean ones that have been cared for properly. I did a swap of them into a SIIG Minitouch so I could have a quiet ALPS board at work and love it. I also did a Blue ALPS swap into another Minitouch but it's too noisy for the cube farm where even Cherry Browns push the limits for being too noisy.
Another commonly overlooked ALPS board that is sweet is the original Apple Extended M0115 with it's Orange ALPS and those awesome key caps that make a thocky chalky sound when you type. Hard to explain but was worth a try. You'd need an ADB to USB converter to use the board on a modern system as they were all ADB.
ALPS have their pros and cons but Northgates stand head and shoulders above anything made today in build quality and only IBM rivaled them back in the day.
