Which Shell Do You Prefer?

Pascal de Bruijn asks: "I recently started to use NetBSD, the first thing I noticed was that it didn't have a command-line history. So I immediately wanted to switch my shell, being on BSD my first instinct was to change to tcsh, but many people told me it wasn't any good. Others recommended zsh. I would really like to hear your opinions about shells." The submitter is particularly interested in shell memory usage, and the features you like...and dislike...from the current options that are available, today.