What would your next choice of writing instrument be?

I have a strange affliction for completeness - if I buy a fountain pen and really like it, I am compelled to search out the matching ballpoint/rollerball and pencil.

I think (note italics) that I prefer the pencil over the ballpoint option, but I'm not always certain.

Pondering this tonight, I got to wondering if I am alone in this behaviour, or do others also hanker after a "set"? If you do, what's your preference for a second item in the set? Pen or pencil, and if it's a pen, which type?