If you like Topre keyboards, the Leopold FC660C is fantastic. Really quality build and super comfortable to type on. A lot better than HHKB, in my humble opinion :)
I bought one about 3 years ago, and I have mixed feelings about it. My FC660C was quite wobbly and a bit scratchy, and seems to takes quite some force to press (leading to hand fatigue). For now I use it as a secondary keyboard, my primary is a Realforce R2 (45g, silent) which I like much, much better (although at a higher cost and larger form factor).
I'm now thinking about lubing the FC660C though, I've heard some people who had incredible results with it. (The typing sounds of lubed Topre keys you can listen on Youtube are just so heaven-like!)
