Keyboard choice is
very personal; an absolute dream for one person is another person's nightmare. As others have suggested, you can go to a well-stocked computer store and try all their models. Unfortunately, in my experience most stores stock keyboards that I personally consider utter and complete junk. (I'm a professional writer, so I spend a lot of time typing at my keyboard, and I've got strong preferences.) I personally like keyboards with mechanical (aka "buckling spring") keyswitches -- most of those you find in stores use rubber dome technology instead. Mechanical keyswitches produce a crisper, "clickier" feel than do rubber dome keyswitches, which are much softer or "mushier."
If you like mechanical keyswitches, check
CVT, which makes the Avant line. These were formerly sold under the Northgate brand. I've got several of the original Northgates and I like them a lot, but I've not actually bought anything from CVT. These keyboards are expensive, though -- the cheapest is $149. Another option is to check
PCKeyboard.com, which sells some models derived from old IBM designs (the sort of keyboards IBM sold with the original PC AT). These are less expensive, at $49-$109. They're available in both buckling spring and rubber dome models. They've got a
Linux model that rearranges the Ctrl, Esc, and Caps Lock keys in a way that some Linux users prefer. (The CVT models can be adjusted along similar lines via DIP switches, and come with replacement keycaps.) Note that I've never bought from PCKeyboards.com; I've just got them bookmarked for any future needs I might have.