Which editor is best?

You should decide which editor is best for you. Pico is easy to use as well as being small and efficient. Emacs and XEmacs are larger, more graphical, and may be more comfortable for people used to MS Windows environments. They also have some extended functionality, including utilities specifically for programming. VI can be very difficult to learn but it is very powerful. Additionally, if you plan on being a system administrator, becoming familiar with VI is important as this may be the only functional visual editor available when a system is malfunctioning.