Shells

No, I'm not talking about seashells. I'm talking about Unix shells. You know, tcsh, bash, csh, ksh, sh, etc. Maybe you change shells regularly, or maybe you just stick to one shell. I personally like the bash shell, or the GNU Born Again shell. I use bash 3.1. Shells differ in syntax, in style, in purpose, and in quality (of course). What shell(s) do you like? What shell(s) do you like to hate?