As I mentioned in the book's introduction, Ruby is my language of choice. It is the tool I instinctively reach for first when solving system administration problems. To recap, it has principally achieved this place in my affections by
Making it simple to write nicely readable code
Emphasizing convention over configuration, so a little effort goes a long way
Offering seamless mechanisms for interfacing with C libraries
Having syntax, extension, and execution conventions that very often make coding the "right" way and the "quick" way the same thing
Adopting object-oriented principles so completely that extremely powerful metaprogramming techniques become readily available
Of course, this enthusiasm could be the result ...