I love drawing with ballpoint pens. They are not a typical fine art tool and are generally used for more mundane tasks such as taking notes or writing checks. They are a product of the modern world, made for convenience and ease of use. They are portable and ubiquitous. You can carry one in your pocket and have the ability to draw anywhere, be it a sketchbook, scrap of paper, or a napkin. As far as specific pens go, I don't have a favorite brand of ballpoint pen, and I honestly think that is one of the great things about them.
Ballpoint pens can produce a depth and richness that you just can't achieve with rollerball pens (see my blog on rollerball pens to read about my use of rollerball pens and associated shading techniques). Ballpoint pens have a paste-like ink that can produce rich velvety blacks. Because of the consistency of the ink, you can use pressure to vary tone. I also draw in a pattern of scribbles similar to how I employ rollerball pens. Using the combination of both pressure and scribbles gives the ability to produce a wide range of gradations. I start out drawing very faint lines and will then get darker, filling in the velvety black areas last.
Some things to be concerned about however is maintaining tonal integrity if producing work for reproduction by printing. The more subtle tones can be lost if not careful, but this goes for any medium. It's also unclear what the longevity of any drawings made with ballpoint pens will be. As far as I know, there aren't any ballpoint pens that have been rated as acid-free or lightfast. This means the inks used may have acids which might damage the paper of the drawing in the long term. Since we cannot be sure if the inks are lightfast, they may fade over time due to exposure to sunlight or UV rays. It would be best to keep any ballpoint drawings out of direct light to be safe. I would also take high resolution photographs or scan of any drawings in order to document or preserve the work.
Do you like to draw with ballpoint pens? How do you feel about ballpoint pens vs other types of pens or drawing media. I'd like to know what you think or see samples of your work.