When comparing Courier vs Vera Sans Mono, the Slant community recommends Courier for most people. In the question“What are the best programming fonts?” Courier is ranked 52nd while Vera Sans Mono is ranked 98th.
Ranked in these QuestionsQuestion Ranking
Pro Clear glyph resolution
Pro Simple yet effective
Pro Comes pre-installed on almost any operating system
This means that the user doesn't have to go to the bother of installing anything.
Vera Sans Mono is licensed under GNU making it freely available.
Pro Clearly distinguishes clashing characters
Characters such as "1" and "l", as well as "0" and "O" are differentiated enough as to not be confusing.