The best keyboard is...
The ideal #keyboard must have a programmable and open-source firmware like QMK. These firmware support advanced features like: macros; distinction between short and long press of a key; additional modifier keys for changing the behavior of other keys; and so on...
Contrary to my initial wisdom, if you have a programmable firmware, then a fancy keyboard with a lot of keys is not important, because every key can have two or more functions. In fact, I didn't programmed the far-away keys at all.
I have an Ergodox keyboard. I'm accustomed to Columnar Layout (i.e. the keys are on a regular matrix), and I cannot go back.
I like a split keyboard, because it is adaptable to the width of shoulders and arms.
I switched to a #dvorak based layout. Now I type with all fingers, in an efficient way, and I don't feel any stress. But, the main difference is not between dvorak and qwerty layout. The root of the problem is that with qwerty I accumulated bad-habits, that I were not able to remove. But switching to a new layout, I were forced to learn from scratch, but this time I started with sane habits.
The drawbacks of a potentially better layout like #dvorak (I like it very much) is that I had to customize many DoomEmacs keybindings, because some key chords and sequences does not make sense anymore.