Keyboards are a very personal thing. For those of us whose job requires their use basically all day, every day, they are the piece of hardware that we have to be comfortable with. A good keyboard will stay with you for years, decades in fact, but PCs will be upgraded and so will your monitors. Microsoft has been producing keyboards since the early 90s, but in all those years there is but one keyboard that remains the best: the Natural Keyboard Pro (henceforth referred to as the NKP). Microsoft has produced one keyboard that was better before then and no keyboards since then that are remotely as good. Some may disagree with me: they are wrong. Keyboard preference is like religion: if someone disagrees with you then there can be no dissuasion.
The first, best Microsoft keyboard was the classic Natural Keyboard, released in 1994. It had a great feel, it was my introduction to the ergonomic layout and it was built to last. I still have four of these in my possession, and would still be using them if I hadn’t switched to the NKP when it was released in 1999. The NKP added media keys and USB support, and although the feel wasn’t quite as good it was a worthy successor. I am still using this keyboard today, the very same item, some fourteen years later. (I don't think I have any other piece of electronics I am still using from that long ago). Like I said, these keyboards were built very well indeed. Those of us who worship the NKP, and we are a substantial band, hoard them. They stopped being manufactured long ago, so it is important to keep the ones we have working, and to hoard any that we see being careless tossed aside by others. These keyboards can and do get filthy after years of use, which acts as a handy deterrent to anyone else wanting to use our machines. I thought my main keyboard was bad (check out the space bar in particular), but then I saw two co-workers NKPs. They looked disgusting, but still work perfectly and will only be taken from their owners from their cold, dead hands.
Mine: not bad for 14yr old hardware
At some point the MS keyboard team seem to lose their collective minds, frankly. They re-arranged the cursor pad from an inverted T to an actual cross, as if moving those keys around wouldn’t matter. They introduced the incredibly annoying F-lock feature, designed to really tick off everyone that used function keys (a tradition that is still going strong, see later). There were even attempts to rearrange Insert/Delete/Home/End layout as well. Over the years the quality of the keyboards just seemed to not be there any more, though this I’m guessing may be related to the falling MSRPs for keyboards in general. For home use I tried a Natural Ergonomic Keyboard 4000 a while ago. It’s kind of a black-colored leather-trimmed successor to the NKP, but the feel was mushy in comparison, and the build quality was missing. After a few months of light use at home the Q-T section actually creaked when I pressed those keys, so I quit using it and gave it to my kids. I got a “fresh” NKP out from my stash and use that instead now. Some co-workers on my team are using these 4000 models, but they don’t look very good as the lettering wears off the keys (I’ve never seen any lettering worn off an NKP).
The keyboard madness continues somewhat into this decade: the Surface’s Touch keyboard doesn’t have them at all, but that’s ok as no-one is going to use that for serious work (eg Visual Studio). However the Surface Type keyboard, which is intended for more serious work, does have function keys, but they default to media usage: you have to actually press the FN key every time you want to use a function key as, well, a function key. The Lenovo Yoga has a similar bizarre feature, but that can be overridden via a BIOS setting.
Will Microsoft ever better the NKP? What will its legions of fans do when their NKPs finally fail (or their kids pour something into them, a more likely scenario)? Will function keys still exist in a decade's time? Who knows. I think I know what keyboard I'll be using though.