Shawn Blanc has written a great, thorough review of three ‘clicky keyboards’ — the Das Keyboard Professional Model S, the Apple Extended Keyboard II, and the Matias Tactile Pro 3:

After a month of using and testing the three most popular clicky keyboards for Mac, I am extremely glad I jumped into these waters. The sound and the feel of a clicky keyboard only takes a few days to get used to, and what follows is this intense feeling of productivity that now accompanies anything I type.

Something I like about mechanical keyboards is that each key has its own unique sound and feel. You could tell how many words someone types, and how many in-line typos they fix, simply by listening. Space Bar, Backspace, Return, and the letters — each produce a unique sound and have their own tactile feel. There is variety when typing on a mechanical keyboard. […]

If you too want to adorn your desk with an ugly keyboard — one with a loud personality and which increases typing productivity — then I recommend the Das Keyboard. I prefer both the tactile feel and the sound of the blue Cherry MX switches, and though I find the Das to be the ugliest of the bunch, a serious typist knows you shouldn’t be looking at your keyboard while you’re typing. 

As for me, I started typing on a mechanical typewriter and on a Commodore VIC-20, and from there it’s been a mechanical keyboard after another, including a fair share of Model M keyboards. When I switched to the Mac as my main system back in the early 1990s, my first Mac keyboard was the not-so-bad Apple Keyboard II (M0487), then the much better Apple Standard Keyboard (M0116); then, when I acquired a used Macintosh Quadra 700 in 1999, it came with the glorious Apple Extended Keyboard II, which I’ve been using ever since, alternating it with the Apple USB Keyboard (M2452) and later with the first-generation Apple Wireless Keyboard, the one that retains the looks of the Apple Pro Keyboard.

I’m not a fan of the latest Apple keyboards. I find them to be great for short typing sessions, but for heavy-duty typing (which is 95% of the time for me) I go back to my Apple Extended Keyboard II or the first-gen. Apple Wireless Keyboard. Now that the Extended II is temporarily decommissioned (it needs cleaning and I have to figure out why the ‘P’ key behaves erratically), I’m using its more compact equivalent Apple Standard Keyboard (M0116). The only drawback of this kind of keyboard is that it lacks function and media keys, but I truly love its size. If you want the most compact and beautifully mechanical keyboard ever built by Apple, by the way, check the Apple Desktop Bus Keyboard (A9M0330), first released and sold with the Apple IIGS in 1986. I have one attached to my Macintosh SE, and it’s a joy to use.

But you know what my secret dream would be? That someone built an adapter to let me use the Macintosh Plus Keyboard (M0110A) with my modern Macs. It’s probably the sturdiest, loudest Apple keyboard available. Too bad it has that quirky, proprietary connector.