When comparing Envy Code R vs Fira Mono, the Slant community recommends Envy Code R for most people. In the question“What are the best programming fonts?” Envy Code R is ranked 23rd while Fira Mono is ranked 51st. The most important reason people chose Envy Code R is:
This font offers very distinct programming characters that help differentiate the following clashing pairs: {} vs. (), "0" vs. "O", and "1" vs. "l".
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Clashing characters are easily distinguishable
This font offers very distinct programming characters that help differentiate the following clashing pairs: {} vs. (), "0" vs. "O", and "1" vs. "l".
Pro Easy on user's eyes
Envy Code R is quite narrow (like Anonymous Pro) but at the same time squarish. The letters are easy to read and offer a pleasant reading experience.
Pro Fills out the space well
Envy Code R also fits more into a given width when compared to Source Code Pro.
Pro Bold font is the same width as the regular weight font
The bold version has the same width as the normal version which is useful for syntax highlighting.
Pro Looks great and is easy on eyes
Almost looks like Source Code pro and works great with Intelli J where Source Code Pro renders all junk on one of the primary IDE.
Very good for people who read code through out the day.
Pro Extremely readable
You can look at the code for hours and hours. The height between lines and the spacing is perfect.
Pro Offers better performance in some Emacs builds
This font is used by some Emacs users on Mac OS X in order to get better performance.
Cons
Con No Cyrillic glyphs
There are no Cyrillic glyphs in Envy Code R which may be an issue for Russian users.

Con Lowercase "w" is distracting
The lowercase "w" is a bit distinct looking due to the narrow nature of the font. This could cause a distraction to some users.
Con Large line height
Compared to other options, Fira has a high line height, which reduces the number of lines you can see on screen at one time.
