Dramatic but also practical
Although I use black or blue-black for business, iroshizuku yama-budo is one of my top choices for less formal and personal writing. The color is a deep red with a touch of blue making it look like what you might get after crushing a purple grape in a white handkerchief. This red is interestingly complex, and dark enough with good contrast for reading easily. I like the more generic translation of yama-budo as "mountain grape" which I associate with the actual color.