I have been using a Logitech Comfort keyboard for years. When it broke a few months ago, I discovered that they don't make them anymore. I tried the Logitech Wave keyboard and it was a horrid shape that my fingers could not get used to, so when it stopped working a few days later I was pleased to get rid of it. I then tried a Microsoft ergonomic keyboard, which looked like my original Logitech one but was truly awful, with stiff keys and a cheap build which made my wrists hurt. After a trip to PC World to look at the alternatives, I tried a couple of Logitech models, and ordered this one from Amazon. It is not ergonomic, but the key action is both positive and light, and I have written about 100,000 words on it over the last few weeks, which has polished up they keys nicely! All-in-all a great looking keyboard which has a great keyboard action. My fingers feel spoilt!
I do miss the dedicated Media keys (these keys are shared with the Function keys), but the best feature is a proper caps-lock light, built into the caps-lock key. Lovely! If only more wireless keyboards included proper lights - it would save a lot of password frustration. I don't know why Logitech don't make more of this feature.
UPDATE: 5 Years on. Almost 5 years to the day, I have ordered a replacement because the keys have started failing (the return key keeps popping off, and the Caps Lock key has just stopped working). I only hesitated for a moment, because it has lasted 5 years and many hundreds of thousands words.