How are the keys on the HP Prime? As good as the ones on the HP-67 and HP-41?
Since I haven’t used either of those, I can’t give a comparison to them, unfortunately.
What I can say is that I chose the HP Prime because of the keys. I have some neurological problems that cause finger sensitivity issues that make it painful for me to use keys where I have to press hard and bottom out to avoid missed key presses, which unfortunately is how standard membrane keypads are. It doesn’t take all that many keystrokes on a regular TI calculator for my fingers to hurt. The Prime has proper tactile domes with a reliable, fairly light touch. The HP-35s, for example, is also tactile, but requires significantly more force. The current TI Nspire keys are tactile, too, but not as nice.
The HP Prime has hands-down the best keys of any calculator on the market right now from any major manufacturer, if you ask me.