Lisp
Lisp has a strange hypnotic fascination. Probably it's for all those parenthesis, the idea that commands, expressions and therefore logical concepts have a beginning and an end. They're not clear, but self-enclosed. Selfish, but in a good way.
Unfortunately, Lisp is not a fashionable programming language anymore. List processing (yeah: lis-p) today seems kinda meh as a selling point. Until you realize that in Lisp everything is a list, therefore list processing means the ability to process anything, code included. That said, let's be honest: being at ease in Lisp requires to think in a Lisp-y way that can't be defined "immediate".
Also, most of the official/popular books on Lisp aren't that welcoming and this doesn't help. The most effective textbook is probably "Common Lisp: A Gentle Introduction to Symbolic Computation" PDF. And the need to specify that it's a "gentle introduction" means something. By the way, it's actually gentle, I'm able to confirm that.
Many Lisp books and tutorials make approaching the language even harder than it should be, essentially for the author's personal tastes in language platforms and editors or IDEs. My very personal advice is to keep everything simple.
First, install SBCL via CLI.
Second, ignore all the stuff about "using Lisp in Emacs" if you're not an Emacs lover already, otherwise you'll spend precious time trying to understand Emacs. Use your favorite editor, you'll always be able to get into Emacs later.
Third, go and play coding.
Lisp is my favourite programming language, for pet projects. Using it is fun and quite rewarding, for desktop applications as much as for things like embedded systems and controllers Arduino-style. It won't make you rich and neither the star of your next developers dinner. But it's really worth a try. And, probably, a good first step to the strange world of modern-ish functional programming.