My favorite keyboard is my DIY silenced (with my Silencing Rings) black HHKB Pro 2 with blank black modifiers and spacebar and blue Topre alphanumeric keycaps. I like both the 60% form factor and the HHKB layout.
Much earlier, I had a first-generation Leopold FC660C. I liked the solid feel and sound, but I didn't like the layout as much as that of the HHKB. In addition, at that time, the keycaps on the FC660C were not nearly as nice as those on the HHKB. However, even with the new improved keycaps on the FC660C, I prefer the HHKB -- again because of the 60% form factor and layout.
As you may know, the switches in the FC660C are mounted to a steel plate, whereas in the HHKB they are mounted in the top plastic case. These differences give rise to a more solid feel and sound in the FC660C and a more plastic/springy sound/feel in the HHKB. I think because of the extra give when typing on the HHKB, I find typing on it to be less tiring than typing on a plate-mounted Topre board like the FC660C.
There are times when I prefer the sound and feel of plate-mounted Topre switches, and so I have a RF87U for this. When I am not typing on a 60% board like the HHKB, I like to use a TKL board. I have never been comfortable with any of the keyboards in the in-between categories, such as so-called 65%, 84-key, etc.