Agreed. They have to have a good way to write it (an IDE), a good debugger, a good profiler, a good library ecosystem, a good community, a good deployment story

Agreed. They have to have a good way to write it (an IDE), a good debugger, a good profiler, a good library ecosystem, a good community, a good deployment story, reproducibility, portability across platforms, etc. I find commercial support helpful as well. Common Lisp has all of that.