Ergonomic is a must. Anything not ergonomic should be gently removed from your approach.
Mechanical is nice, but relates to how your personal interaction with your tools is. I use Cherry Blue or similar. I personally want to feel that click. I also learned to type on a 1940s Royal typewriter. Cherry Red aka Linear feels awful. Connect any dots you like there.
TKL designs with f keys and arrows are ideal for emacs users imo. Anything less feels either for non programmers or for people who use keychords a good deal less. The really cranked down designs seem more for writers than coders- special characters are in layers.
I have used Kinesis keyboards for a few years now. Their Edge RGB is _very_ nice. After an RSI episode earlier this year, I moved to an Advantage 360 SmartSet. I consider their SmartSet system to be ideal in terms of a very good meet point of configurability, ease of use, and reliability.
Re the 360, I am not as convinced of the Ortho layout or lack of f-keys. The thumb keys work well.
I would recommend Kinesis as a professional keyboard vendor.
In any case, this becomes a personal geometry problem where your hands, arms, shoulders will all combine to make a physical keyboard better or worse. This is further fit +/- by the tools we use. So it's very individual. Hope my experience shared here help someone.