Bash is now a superset of Ksh
One might argue on this differently, depending on which implementations of Ksh and Bash that you have locally installed, but from what I can tell, Bash has long passed up Ksh, which as far as I can tell, has been dormant for years on features.
The shell with the largest set of features that I know of is zsh. I would argue that Bash has plenty of features inherited from that shell as well and is more than rich enough in capabilities, definitely for every day use.
Zsh has a mass of features found in Bash, Tcsh, and all of the other powerful shells. I find it to be a bit overwhelming, and I have no need for all of the features it offers. Bash has more than enough features for me, and I can even make due with a smaller shell, as long as it has UNIX System V Bourne Shell equivalent features (The Korn Shell is fine in this respect).
