all time fave is the zebra ballpoint. they are small, fine tip, smooth, and i like the way they look. my grandfather always had one in his shirt pocket so they also make me think of him.
honorable mentions:
i do a ton of color-coding for work and use paper-mate flair felt tips for that. love them.
i just bought my first fountain pen, a kaweco sport, and itโs beautiful and much less scary than i thought a fountain pen would be.