Awful keyboards I've used --
Commodore CBM.I learned BASIC on this beast -- when I wasn't playing Midway. Technically a full-stroke keyboard, after a while you could feel keys wiggle and scrape their way down... and after a while longer, press one wrong and it might not come back up on its own. I think the foley for every movie and TV show computer keyboard in the early 80s came from this thunker.
IBM PCjr I once had to support a lab with twenty of these execrable machines, each with the memory upgrade and parallel port sidecar modules. And when the lab was first set up, the keyboards were left wireless. Not a good idea. Fortunately, I only had to use these disasters when the machines were screwed up; unfortunately, that was often. But that's easily forgiven -- most of the time I got to use an IBM PC, XT, AT, or PS/2 Model 25. Those were happy days, indeed.
Trash-80 CoCo.My first computer. Had it for two weeks, during which I wrote a "track and field" game which involved "running" by pressing two keys back-and-forth as fast as possible. Maybe the worst keyboard ever, but I Did Not Care, because I Had A Computer. Then I got a real computer with a real keyboard (alas, not the IBM I wanted, but at least it had springs.)
Apple IIgs.
Sure, vastly superior to its contemporary IBM PCjr, and some people actually thought it was better than the noisy heavyweight IBMs... those people were wrong. I don't know if it was Apple that began the assault on the spacebar, but they certainly popularized it.
BTW, I've at least briefly used eight of the ten keyboards on that PCWorld list. (Timex Sinclair 1000 and Mattel Aquarius are the holdouts.) Yes, even the Commodore PET with the built-in cassette drive.
It's hard to remember specific awful keyboards since then -- such an auspicious beginning tends to reduce everything else to a vague blur. My first clone had a Chicony, I didn't think it was awful at the time; I gave my second keyboard a wicked-cool Make It Stone! paintjob. Then I bought an M15, and another one for work, and... well, there's been a lot of really good keyboards made, but the intersection of adjustable-ergonomic and buckling-spring is a pretty small space, and once you're in it you don't want to leave.
I do remember when the entire industry made the shift from mechanical to rubber-dome switches -- for a while KeyTronic held out and commanded a premium based on their name, but eventually even they caved. Dark times. Almost overnight, nobody gave a damn about the keyboard anymore.
Sigh.