The main reason for me to choose Fira Code v5 is the fact that certain glyphs ligatures in Fira Code v5 support multi-character combinations while seemingly display a seamless character(!) Nice!!
Hack does really come in on a very tight close shared 1st place but does not support seamless multi-character ligatures.
Changing your favorite programming language font (in my case ST) really does help present your code better, cleaner and enhances readability.
As soon as you switched the default font for something else you prefer, you will never go "Courier New 9" again ;-)