My compilers prof said #1 thing about this career. Take care of your back. He messed his up from years of poor posture hunched over looking at screens.

I don't really understand the choices. Is a laptop that is normally docked on a desk considered a desktop for the purposes of your question?

For work I use a work provided laptop, mostly folded on my desk with an external monitor and keyboard and mouse.

At home I use a Macbook Pro.

Because of the RAM cost rises and desire to run LLMs locally, I have considered a mac mini or some other desktop mac instead of upgrading my macbook pro. (Since loading it with 64GB of Ram now has a purpose is probably didn't for me before.)

The most important thing for posture is to have a good office chair (herman miller Aerons are cheap used) and lift weights at the gym. A regular deadlifting (once per week) builds a strong back and core and keeps your posture in check.