So what am I using? The shell is Fish. Most Linux distributions and OS X come with Bash being their default shell. And to many users, that is the only shell they have ever known and don’t know that alternatives exist. Fish is one of those replacements.
My primary reason for using fish is I like its built-in tab and auto-complete features. And it has nice colors out of the box that makes using it more pleasant. It does nothing super special that can’t be done with Bash, but it does these things without major tweaking.