One of the things I'm very particular about is my writing utensils. I prefer to write in pencil when possible. It has to do with the way the writing tip feels as it moves over paper and the things you can do with graphite. Also, graphite is more erasable than ink. Being a liquid or gel, ink can't provide the same feel and effect. By my second year of college I realized that I like the 0.5 mm leads rather than the more common 0.7 mm. It makes a very fine line though is more brittle and requires a lighter touch. A few years ago I settled on the Zebra M-301 and I now own several. They are simple yet have the very high manufacturing quality and durability of Japanese design. Look at that metal cylinder!
I also own Zebra F-301 blue ink pens but despite looking similar and obviously sharing common parts they aren't as good as the pencils. It is merely an expensive ball point pen, though the design does seem durable and I assume I could get refills for it. I don't have a favorite ink pen design although I prefer fine point when I buy new. Zebra does not make fine point pens but they do have some nice looking gel pens that I suspect write smoothly. Maybe someday I'll find the perfect fine point pen to go with my mechanical pencils? I'm open to suggestions.