Both ECL and GCL are descendants of Kyoto Common Lisp. That said ECL (generally speaking) is a complete as ANSI Common Lisp implementation[1], has more "man yea

Both ECL and GCL are descendants of Kyoto Common Lisp. That said ECL (generally speaking) is a complete as ANSI Common Lisp implementation[1], has more "man years" under its belt, has active community, better support across platform, is recognized by Common Lisp developers and has more "man years" under its belt. [1] One of current GCL goals is to reach it