When comparing Google Droid Sans Mono vs Hack, the Slant community recommends Hack for most people. In the question“What are the best programming fonts?” Hack is ranked 7th while Google Droid Sans Mono is ranked 24th.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Makes code very easy to read, especially if using the version where zeroes are slashed
Feels very easy to read code, even in a very small px (like 10 or 9). Letters are slightly separated, l (ell) and 1 are different, " (opening and closing quote) is straight and not angled, and the "Zero Slashed" version makes it an excellent font for coding.
Pro Size and spacing are excellent for readability
Very easy to scan through code. Large character size for fonts of the same type size.
Pro Looks neat
Droid Sans Mono looks beautiful. The only disadvantage is that there's no italics or bold.
Pro Very readable
Pro Libre webfonts are available in svg, eot, ttf, woff, and woff2 formats
Hack is free for unlimited commercial and non-commercial use. The webfonts are hinted (TrueType instruction set) to optimize display on the screen and are built into all commonly used web font formats with each new release. They include the complete release character set and smaller (filesize) basic Latin subset releases. They are available in the build directory of the repository.
Pro Fixes many readability issues in Vera/DejaVu
The tilde symbol ('~'), comma (',') and semicolon (';') glyphs have been modified to be more readable at small sizes and/or on non-HD displays. In addition, the underscore symbol ('_') has been slightly lifted for alignment with surrounding characters.
Pro Avaliable in many GNU/Linux distro package manager
Including Debian/Ubuntu (fonts-hack), Fedora (font-hack-ttf), OpenSUSE (hack-fonts), Arch (ttf-hack) and probably many more. Much nicer than having to manually install/update
Pro Free/Open license
Pro Renders accurately on Windows on all font sizes
Pro Based on the tried and tested Bitstream Vera Sans Mono
The fonts are in the Vera Sans Mono lineage with a significant expansion of the character set (which includes Cyrillic and modern Greek character sets), new glyph shapes and modifications of the original glyph shapes, as well as improvements in metrics and hinting/TT instructions to make it more legible at small text sizes used for source code.
The changelog is available here.
Pro Powerline glyph patch is included
The regular set is patched with Powerline glyphs by default. There is no need to patch the font to use it in Powerline environments.
Pro Source code is released in UFO format
UFO source format is widely supported by all modern font editors if you would like to modify the typeface.
Cons
Con Zero is not slashed or dotted
This can make it hard to distinguish the letter "O" from the number "0".
Con Superceded by Google Noto Sans Mono
Con No ligatures in the default font
Although patched versions with ligatures do exist - see here.
Con Sometimes difficult to distinguish lowercase "i" (eye) and lowercase "l" (ell)
When using a higher resolution monitor and a smaller font size, the lowercase "i" (eye) and lowercase "l" (ell) are very difficult to distinguish. The space between the dot and the remainder of the letter seems to somehow disappear, thereby making it look like a solid line, similar to the lowercase "l" (ell).
Con Too similar to DejaVu
See this gif comparison between the two fonts.