Logitech UltraX Premium
- feels like laptop keyboard with steady, very good balanced, response
- flat, very comfortable
- ps/2 compatible!
- has some basic media keys for adjusting volume without having to leave fullscreen
I play with ESDF + space for jumping and that keyboard helped me improve my strafe jumping a lot as response is very quick and you don't get "stuck" due long button way. After one year of excessive usage its still in perfect condition.