Fira Mono vs Iosevka

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.

You can look at the code for hours and hours. The height between lines and the spacing is perfect.

This font is used by some Emacs users on Mac OS X in order to get better performance.

Iosevka is very clear and legible on all displays and in all sizes.

Narrow character width uses horizontal screen space more efficiently.

This font comes in seven different weights, ranging from thin and extra-light to heavy.

There is full customization of styles and variants in Iosevka.

Iosevka is quite flexible in that it supports Cyrillic and Greek letters.

Iosevka is free and open source.

Includes characters for supporting Powerline/Airline for terminals and terminal editors.

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.

Many of the common styles are available, including Sans Serif and Slab Serif with normal, bold, italic, and bold italic styles.

IPA is a system containing the sounds of spoken language and includes speech qualities such as intonation.

Due to it being readable on all types of displays, Iosevka isn't hard on the user's eyes.

The developer is active and responds to user questions and issues.

Iosevka integrates CJK characters well, those being characters of the Chinese, Japanese, Korean, and occasionally Vietnamese languages.

For better reading longer texts.