Emacs lisp is one of the worst lisps for most things, though it's a decent fit for its specific purpose. People are suggesting clojure and clojure is great but

Emacs lisp is one of the worst lisps for most things, though it's a decent fit for its specific purpose. People are suggesting clojure and clojure is great but it also has rigorous immutability semantics. If you're not familiar with that model you'll spend as much effort learning it as learning lisp, and it'll be unclear which things come from lisp weirdness and which from immutable weirdness. Someone will also probably suggest racket, which has its strengths as a learning language but is also very large and complex, with numerous extensions to the core language that make it kind of a disorienting ecosystem. I like janet a lot. It uses "normal" data structures as its primitives rather than the traditional cons cells. So if you want to understand and be connected to historical lisp it will feel very different, and be a poor choice. This also applies to clojure though now that I think of it. otoh if you just want to use parens & prefix notation and play with macros either will work.