[nicklecompte]

Racket might be the best bet, especially since it comes with a graphical IDE - Emacs is a big stumbling block for beginners. Racket also has lots of tools that make it fun and practical for learners (e.g. creating static websites, simple GUI applications). Things like this seems like the best way to learn without getting bored or frustrated: https://docs.racket-lang.org/quick/

[rbc]

It depends on the kind of beginner. GNU Emacs has a built-in tutorial to get started on using the editor. After that, there's an introduction to Emacs Lisp as part of the info documentation in most packaged versions of Emacs. Extending Emacs is as practical a way to learn Lisp as others.