Pen?
@freemo @olives The PEN IS mightier than the sword.
All jokes aside, I keep a Zebra F-701 and F-401 with ultra fine black carts. Those are for Mathematics. I keep M-301s for dragging graphite rods against an abrasive surface. A Permanent Marker is a must and I only use the large one to accidentally write on a whiteboard. (Professors think it's magic when they see Expo solvent remove it.)
I also keep a G2 ultra bold black, 1.0mm I believe, that's for Hanzi. Anything other than that pen and I will mess up the strokes. A Fountain Pen is something I love to hate. I have several Cross Pens but I don't like fancy mediocrity, it's a cod piece of a pen. Parker Pens feel a little better in my experience but Zebra has really black ink and the heavier F-701 just glides across paper. It's also not a weapon and the knurled steel grip is the only acceptable grip.
A pen is a tool and every tool has a specific use. If someone doesn't have a preference in pens, perhaps it's because they don't write often.
@olives
Yes I am planning on running from presidents.