When looking for a mechanical keyboard, figure out what features you want and what switch is best for you.
Features are like USB ports, macro keys, backlighting, media keys, etc.
Switches are the "springs" underneath the keys, and the different colours of them have different qualities. There are four main switches, though there are a couple more that are pretty rare to find.
- Blue: generally considered best for typists. They are loud, clicking at the actuation point (when the keyboard registers the keystroke) and when bottoming out (pushing the key all the way down). Can clearly feel the actuation point when pushing down.
- Brown: Basically Blue switches but don't click at the actuation point. So if noise is a concern these are a good compromise between a Blue and Red.
- Red: Considered best for gaming, these are moderately loud keys (Brown level) that have a much more linear travel then Blue/Brown. You cant feel the actuation point as well.
- Black: Like Red switches, but an even smoother travel so you cant feel the actuation point and require a bit more force to push down. Quieter than Red's and offer the most natural transition from a membrane keyboard.
Might want to take this quiz, based on your answers it will recommend a mechanical keyboard it thinks is best for you.
http://mechanicalkeyboards.com/first_mechanical_keyboard.php
I personally use a Ducky DK9008 Shine II with Brown switches, and am quite happy with it.