I ran a survey on a couple of the mac lists I am on, and to my surprize no
clear winner emerged. Somebody liked every single model the best. The
extended II is what I am typing on right now, and in "most" cases I like it
about the best.
Typically to test a keyboard I use it myself for a few days, so I have
tried a LOT of different keyboards. This includes PC keyboards since my
Starmax (mac clone) can use PC or mac keyboards and mice, both at the same
time in fact.
I may not know what the best keyboard is, but I do know the sure path to
insanity, a real expensive keyboard, ie Apple Adjustable ergonomic thing
that sells used for about $50, that has one slightly flakey key that you
think maybe using for a couple days may sort out.