Well, over the years I have tried many keyboards. As a computer geek, I've probably tried plenty keyboards over many different computers. What do I find to be my favourite keyboard? The first question would then be: what kind of keyboard do we speak of? Laptop keyboards? Desktop keyboards? Since I believe they are both of different categories, I'll give you a favourite keyboard for both. Recall that this is my opinion, and I welcome you to leave your opinions in the comments or the tagboard.
Personally, I find that my favourite keyboard in the Logitech Elite Keyboard. For one, it is the one I am most used to. For some reason of another I find it rather comfortable to use and I seem to type the fastest on this keyboard. It is quite quiet at first, then becomes a little noisy as time passes and dust and dirl gets trapped under. No worries - all you have to do - is open it up, easily enough, clean the keyboard, and it becomes all nice and quiet again.
This keyboard also happens to have quite a number oif function keys as well as a scroll wheel! While the kind you most often find happens to be a wired USB one, the one I have at home in Malaysia is wireless. It is paired with the MX700 in the MX Duo set, and I find that they both are great input devices. When I came here and decided that I needed a proper full sized keyboard, I went shopping. Never in my mind would I have realised that something like this would actually be still be in the market!
Then we come to laptop keyboards. My favourite of all still has to be the Apple Powerbook laptop keyboard. I believe the iBooks and MacBooks are similar, so this might apply to them too. I find that the nicely sized keys and the travel distance of the keyboard is just quite difficult to find in a laptop of similar stature. The cosmetics of the keyboard being so nicely matched with the laptop, regardless of the colour, just completely means it beats the IBM laptop keyboard (another one I favour highly) hands down. Of course, we have the issue of Apple laptops having very few buttons besides the keyboard and the power button. But that problem is easily fixed regardless which operating system you happen to use. :D
What is your favourite keyboard?