Just out of curiosity, as some people have a preference on the shell they use, and Apple changed their mind away from TCSH in 10.3 and 10.4 in favour of Bash (although TCSH is still present, of course).
Whatever is standard . Anything that has tab completion does it for me.
So that includes:
On root on FreeBSD boxen you have csh as standard shell. For user it is sh, so i usually rig my login scripts to exec csh. Bash is standard shell for root and user on linux, where they don't have sh, so sh is just a symlink to bash. (which BTW causes a lot of Linux scripts to break under FreeBSD as it is calling the real sh, not bash).
on any machine that I setup I always use tcsh, the exception being on my mac and thats just cause I am too lazy, I will probably change it soon though.
the main reason why I prefer tcsh over bash is history completion
if you type in a command and run it you might want to run it again, in both tcsh and bash from a blank prompt you can press the up arrow until you find it.
if however you type in one character of the command and press up in tcsh or bash they now act differently, bash will just go to your previous command. tcsh on the other hand will use this character to narrow the search of your previous commands, so you will be able to search a smaller subset of your command history for the command you want.
This one thing is the reason why I prefer to use tcsh over bash.