When comparing Fantasque Sans Mono vs Iosevka, the Slant community recommends Iosevka for most people. In the question“What are the best programming fonts?” Iosevka is ranked 6th while Fantasque Sans Mono is ranked 27th. The most important reason people chose Iosevka is:
Iosevka is very clear and legible on all displays and in all sizes.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Italics look good
The handwritten-style italics of Fantasque Sans Mono are quite attractive.
Pro Open source
Fantasque Sans Mono is open source, meaning it can be freely used, changed, and shared by anyone.
Pro Uniformity
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.
Pro Support for various platforms
There's support for OS X, Linux, and Windows (otf, ttf) in Fantasque Sans Mono.
Pro No useless experiments with special characters
Pro Own personality
It looks distinct, playful. But don't cross the line when it becomes unusable.
Pro Lowercase "k" looks nice
Pro Glyphs support
This is good for those who wish to use different designs of a certain character.
Pro Has ligatures
Alpha version supports ligatures as Fira Code does.
Pro Truly compact
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 ).
Pro Cyrillic alphabet support
This is useful for those who wish to use letters from certain Eastern European or Asian alphabets.
Pro Webfonts included (eot, svg, woff)
Webfonts, such as eot, svg, and woff, are included in Fantasque Sans Mono.
Pro Powerline symbols
Pro Readable
Iosevka is very clear and legible on all displays and in all sizes.
Pro Narrow
Narrow character width uses horizontal screen space more efficiently.
Pro Large number of weights
This font comes in seven different weights, ranging from thin and extra-light to heavy.
Pro Great customizability
There is full customization of styles and variants in Iosevka.
Pro Support for Cyrillic and Greek letters
Iosevka is quite flexible in that it supports Cyrillic and Greek letters.
Pro Free and open source
Iosevka is free and open source.
Pro Powerline support
Includes characters for supporting Powerline/Airline for terminals and terminal editors.
Pro Ligature characters look great
Few fonts have a good ligation feature. Ligature characters (such as æ or the German ß) are supported in Iosevka and look just as you'd expect them to.
Pro IPA Support
IPA is a system containing the sounds of spoken language and includes speech qualities such as intonation.
Pro Several styles available
Many of the common styles are available, including Sans Serif and Slab Serif with normal, bold, italic, and bold italic styles.
Pro Easy on user's eyes
Due to it being readable on all types of displays, Iosevka isn't hard on the user's eyes.
Pro Well-maintained
The developer is active and responds to user questions and issues.
Pro Good CJK compatibility
Iosevka integrates CJK characters well, those being characters of the Chinese, Japanese, Korean, and occasionally Vietnamese languages.
Pro Also variant with tiny serifs available ("Slab")
For better reading longer texts.
Cons
Con Lowercase "i" (eye) is tailed, and too similar to lowercase "l" (ell)
Same with Hack and Ubuntu Mono.
Con Lowercase "k" is ugly
The lowercase "k" seems like a strange "r" since it has a line that extends to the top of capital letters. There is currently a workaround aiming to correct this.
Con The size is too small
Letter size is smaller than other fonts at the same setting.
Con Too narrow
Con Must do a custom build to get all ligatures
Con Fewer ligatures than other fonts
Iosevka has a nice ligation set, but it doesn't have as many ligatures as fonts like Hasklig, Monoid, or Pragmata Pro.