I write a lot. All day in fact. Most of the time, it's stuff I'm not particularly excited about. I write evaluations, grade tests, write comments on essays. I write notes to myself, notes to other people, notes that will never be read.
I write elaborate essays that I forget I've started. Sometimes I make lists. I write notes on top of notes. I write rough drafts and final drafts.
I do it using whatever pen or pencil I happen upon when the need arises. Over the years, I've become very partial to two types of pens: the ones that release ink in a similar fashion to the old-style nibs, and gel pens. They both roll onto the paper nicely, and generally give a nice and positive experience with the writing process.
Nevertheless, my favorite pen, the best pen in the universe, happens to be the cheapest. It is the cheapo plastic Bic pen, preferably blue, with a medium point. It also has a second use when you're done with it. The blue cap on the end pops off and you can pull the nib off so that you're left will a hollow tube.
It's perfect for shooting spit balls.