Personaly i found abcl a bad experience.
Thoughts on ecl & clisp ?
sbcl works nice & fine. But i’t’s the only lisp implementation i know.
There are good books on racket-scheme & chez-cheme.
The only book i know for lisp is, “Common lisp , a gentle introduction to symbolic computing”.
Can I ask what you mean by CLISP being dead? The last stable release was 10y ago yes, but development continues to this day and beta releases are available. Nixpkgs actually ships a beta version by default now.
I maintain a Nix scope with hundreds of Common Lisp packages and I am actually about to merge a dev branch that introduces CLISP support for all packages & their tests; it holds its own pretty well: https://github.com/hraban/cl-nix-lite/tree/clisp. see the list of all packages in the lisp-packages-lite.nix file).
CLISP development: https://gitlab.com/gnu-clisp/clisp
Well, I was judging by its official page and Sourceforge activity, which seems negligible. However, Gitlab also does not seem very active (6 commits this year, despite lots of open bugs). The development is almost stalled. It is on life support, at best.