Good question. Actually, yesterday I started to consider getting the 20-core GPU version (the most expensive one), but only if I decide to get into 3D seriously once and for all. I'm giving myself some time to think about that, as it would mean a lot less web development work, which I love with ProcessWire. As long as Ryan is around, I don’t think I will ever leave PW, but if I switch my main focus, then obviously I won't have as much time to work on ProcessWire-based projects.
As for web development, I am pretty sure that even the cheapest M4 Mac mini would be just fine. My daughter's original base model M1 MacBook Air is at least twice as performant as my current 2019 Intel MacBook Pro in almost all respects, and the latter is still perfectly fine for DTP and web development. So why spend the extra money on features I do not use?
However, I still want to replace my current Intel Mac, as I would like to make more homemade videos from our family footage recorded over the years, and any M series Mac is a lot better for that than my aging Intel CPU based laptop.