I've logged more time on my HHKB than on any other keyboard in my collection. It embodies a near-perfect combination of keyboard elements, including a 60% form factor, switches with excellent tactility, dye-sub PBT keycaps that form an integrated functional unit with the Topre switches, and of course the HHKB layout, which is without a doubt the best configuration I have ever tried. The HHKB is even better after installing Silencing Rings and lubing the switch rails and stabilzers with Superlube 51010.
Nevertheless, despite my overall satisfaction with the HHKB, lately I have been very happily using my refurbished Northgate Omnikey 101. My refurbishing consisted of opening the switches, sonicating the top housings and sliders, washing the springs and contact leaves in 70% (v/v) isopropyl alcohol, lubing the slider rails and contact leaf side of the sliders, painting the top case matte black, swapping the mods and spacebar with blank black ABS caps from Matias, and swapping the Esc, F5-F8, Nav island, and the keys surrounding the NumPad number keys with Tai-Hao BOW doubleshot ABS. The other caps are the stock doubleshots, but cleaned.
After acclimating to 60% boards, I thought I would never revert to a full-size keyboard, but the Northgate is such a joy to type on that it has changed my mind. The sound and feel of the switches is like a hybrid between the best aspects of Topre and IBM Model F. And although I have it remapped to a HHKB-like layout, I enjoy looking at the full array of keys and being able to choose among various options for accomplishing the same task.
The silenced and lubed HHKB is still my overall favorite, but the refurbished Northgate has moved into my rotation as my second favorite board.
It will be interesting to see what happens when my new F62 arrives.