I used to use the Microsoft Natural keyboard Elite, from probably around 1998 until late 2011, when the one I had at work broke and I couldn't find a suitable replacement. I tried one of the other Microsoft ergonomic keyboards, and found it to be lacking. I've since switched to the Kinesis; after a lot of consideration as I was worried I would spend a lot on a keyboard and not like it, but I am incredibly satisfied with it. I have one at home and one at work, and now prefer typing on it to anything else. It is also assembled in the USA, which I count as a plus.