Inks are by far my favorite part of all this. Sailor Manyo Shirakashi is my favorite ink, I am particularly fond of complex shaders like Sailor 123, 280, Haha, Yurameku line etc. and Birmingham Pens Eroded Bronze, Antique Sepia, and Hydrangea.
My collection of different colors has taken off after I started also painting with fountain pen inks in a watercolor style.
Did you know that you can compare the inks listed here with your own (i.e. only show those that the other owns that you don't) if you create an account on the site and enter your inks? You can sign up here.