The default installation of R on Windows uses Courier New for the console font. Unfortunately, this font offers low contrast between the letter ‘l’ and the number ‘1.’ There is also poor contrast between the letter ‘O’ and the number ‘0.’ The contrast between period and commas is OK.
Lucida Console is an improvement. It has high contrast between ‘l’ and ‘1’, though ‘O’ and ‘0’ are still hard to distinguish. But my favorite console font is Consolas. It offers strong contrast between ‘l’ and ‘1’, commas and periods, and especially between lower case ‘o’, upper case ‘O’, and the number ‘0.’
Consolas is more legible while also fitting more characters into the same horizontal space. It can do this because it uses ClearType anti-aliasing while the other two fonts do not. Here is a sample of the three fonts magnified 4x to show the anti-aliasing.
I found setting the default console font in R a little tricky. Clicking on the Edit -> GUI preferences menu brings up the Rgui Configuration Editor. From there it’s obvious how to change the font. However, what I found surprising is that clicking the “OK” button only changes the font for the current session. I can’t think of another application that behaves analogously. To set your choice of font for all future sessions, click “Save” rather than “OK.”