What 30,000+ hours of typing has taught me about keyswitch feel

A frequently pondered question is what type of keyboard key is the fastest to type on?

That's the wrong question. The right question is...

   what type of keyboard is the fastest to type on comfortably?

TLDR - For comfortable speed typing (120wpm+) the essential element is a way to avoid slamming into a hard key bottom - either by floating (avoiding the key bottom), or by bouncing off a cushioned key bottom, or both. 

As a 120wpm life long computer programmer, my personal two favorite key mechanisms are the Kailh low profile blue clicky switch, and the Keychron B1 series scissor-membrane switch. However, this is as much a product of muscle memory as mechanism. The thing that makes a key mechanism comfortable is that YOU can type on it without hitting any hard bottom.