Note that even the Model M buckling spring mechanism is a step down from the earlier Model F buckling spring, which some people consider to be better. Personally I have not tried the latter as any surviving examples are quite expensive. But the mechboard world is a never ending hole, at least until you hit working beam springs, I think. :)
I had a model F AT, but sold it; it was a truly amazing keyboard, but the layout was a little too weird for me to get used to. Beautiful feel, though, and a satisfying wonky clonk sound.
