Personally, I tend to use either Rhino or Illustrator for my actual design work.
I’ve used OpenSCAD a fair bit in the past for parametric work, although I have less call for that these days.
I’ve also found Deepnest.io to be an excellent nesting program, and you pay what you want for it, which is pretty much unheard of in terms of nesting software. It takes some fiddling with to get it working how you want, and it’s not necessarily the absolute best nesting program out there, but it’s good enough for most purposes.
What about you guys?