Fantasque Sans Mono vs Hack

The handwritten-style italics of Fantasque Sans Mono are quite attractive.

Fantasque Sans Mono is open source, meaning it can be freely used, changed, and shared by anyone.

As a "Mono" font, Fantasque is uniform in size and overalls. However, if you look further into all characters, you'll find that there's almost no pattern between them - except for the huge amount of curves. That said, this font is a very strong contender in terms of readability, especially in a world that seeks pattern (often too much).
An example:
Double single quotes vs single double quotes. In JavaScript code, you can find empty String initialization a lot. Unless syntax highlighting makes it clear, it's pretty hard with other fonts to spot the difference between double single quotes and single double quote.

There's support for OS X, Linux, and Windows (otf, ttf) in Fantasque Sans Mono.

It looks distinct, playful. But don't cross the line when it becomes unusable.

This is good for those who wish to use different designs of a certain character.

Alpha version supports ligatures as Fira Code does.

The Height line is quite short but coherent. You have to like the style but this is one of the most readable at a small size ( 9pts ).

This is useful for those who wish to use letters from certain Eastern European or Asian alphabets.

Webfonts, such as eot, svg, and woff, are included in Fantasque Sans Mono.

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.

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.

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

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.

The regular set is patched with Powerline glyphs by default. There is no need to patch the font to use it in Powerline environments.

UFO source format is widely supported by all modern font editors if you would like to modify the typeface.