I will go out on a limb and say that the Pilot VBall Grip Extra Fine is possibly THE definitive pen for the hpda. I’m always a fan of the Pilot G2, and the new G2 mini seemed perfect for the hpda, but it doesn’t come in fine point, which I consider a must.
Enter the Pilot VBall extra fine. This pen carves fine lines into index cards like it’s giving them a new tattoo. If you can (and like to) cram as much tiny handwriting as possible onto your cards, consider picking up a pack of these at your local
productivity pr0n office supply aisle.