For what it's worth, I use an Ultimate Hacking Keyboard (UHK, https://ultimatehackingkeyboard.com) and I really, really like it (have been using it for about 6 months now). I do not like the "ortho" keyboards, and I definitely need my keyboard to be split in the middle.

What I love about the UHK is the programmability: I can make the keyboard do lots of things, which makes switching between OSs much easier. The UHK makes heavy use of the "layer" concept.