Racket but I’ll take Guile Scheme as a close second. Then Hy, a lisp dialect of Python. I’m writing a blog written in a DSL of Racket right now, Pollen, that makes authoring a joyful experience. Hy gives me access to the entire Python ecosystem plus access to things like macros. Guile Scheme is the configuration language of the Linux distribution, Guix System. Guile’s G-Expressions are so powerful for writing packages.