[Etheryte]

As an anecdotal example, Teensy is often found in custom built mechanical keyboards and mechanical keyboard kits. Form factor and library support are two primary reasons as far as I've understood in my occasional bouts with hobbyists.

[alpaca128]

And their official software to flash the firmware is excellent. I've had severe issues with cheaper controller boards where the pain isn't worth the price difference in my opinion.

[mamcx]

I pick teensy for mine. Is null-issues and so easy to flash.

Also exist a neat workflow where you design your keyb on http://www.keyboard-layout-editor.com and then import it on https://kbfirmware.com and you get your keyb up and running very fast.

[neltnerb]

Well, there was that short lived issue where the Teensy 3.5 or 3.6 wouldn't boot right without an extra capacitor soldered on the reset line.

But it's also very encouraging that on the Teensy the issue was identified and a solution provided so quickly.

On the responsiveness note, I found a typo in the ESP32 datasheet and reported it to them through the forum. They responded very quickly and noted that it was indeed a typo (their chip as described didn't have a ground pin) and promised to fix it.

So on speed that's great. But their most recent datasheet had the same typo so...