Shell wars are, in the end, no more interesting than editor wars.
+1. One person's "fully-featured software" is another person's "ten pounds of crap in a five-pound bag".
Bourne-family shells
All of which, considered as programming languages, are badly designed, in the usual way of sofa beds and other allegedly dual-purpose pieces of furniture. Scsh is a shell that's a high-quality programming language (namely Scheme), and I have just discovered xonsh, which is like scsh for Python. I have some ideas for a shell based on rc and Lua.
To my mind, the Research 10/e sh had it about right,
Unfortunately, approximately nobody except you has access to its man page. Can you post or email it?