Adobe Source Code Pro vs Fantasque Sans Mono

The characters in Source Code Pro are easily readable. They have consistent widths across all weights as to not break up words. Commonly used programming symbols (such as various kinds of brackets) are made easily discernible from each other while various punctuation marks are made bigger than normal. This makes them especially good for programmers who keep staring at code for hours.

The characters have been made in such a way that they are easily discernible and usable regardless of font size, weight, and display.

The font is licensed under SIL open font license with source code available on GitHub. Being an open source font, it's also reasonable to expect incremental upgrades and additions to character sets and functionality.

Characters are evenly spaced, making for better readability.

The font works particularly well when it is in print.

The code comes with seven style variants: ExtraLight, Light, Regular, Medium, Semibold, Bold, and Black.

The beta release version of Source Code Pro introduced italicized characters on Jul 18, 2015.

The font is hosted on Google Web Fonts directory, meaning that it can be easily embedded in web pages.

Powerline symbols are useful for programmers to display a nicer status bar or mode-line on Vim and Emacs.

A version of Source Code Pro with support for common Haskell composite glyphs such as >>= is available here. An editor with ligature support, such as Leksah, is required.

The Light and Extra Light weights make the font less "bold" looking when reading.

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.