I'd throw in a plug for the Dumang DK6 here (which has become my daily driver keyboard). It seems to be the spiritual successor to the Ergodex, only with a lot of modern updates- hotswap MX compatibility, neodymium magnet attachment method, fast polling, LEDs for those who like that kind of thing.
I remember reading about the Ergodex when it first came out, and wanted to find one.