When comparing Proggy Clean vs MonoLisa, the Slant community recommends Proggy Clean for most people. In the question“What are the best programming fonts?” Proggy Clean is ranked 42nd while MonoLisa is ranked 54th. The most important reason people chose Proggy Clean is:
All characters are completely readable in the smallest size. Perfectly usable in terminal and code editors in 12px text size.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro The easiest to read
All characters are completely readable in the smallest size.
Perfectly usable in terminal and code editors in 12px text size.
Pro Hipster among hipsters
Even hipsters will marvel at this font, praising you as the new hipster lord. It is best at around 19px (tested on Mac). Overall, it has better readability than many default fonts.
Pro Customizable OpenType features downloads
The website offers customizable downloads for editors that don't support OpenType features natively.
Pro Script variant
It comes with script variant for italics.
Pro Ligatures
The typeface supports over 120 optionally enabled ligatures for common coding tasks.
Pro Italics
The typeface comes with an italic version.
Pro Space
Space used by the characters has been carefully balanced to keep them light to read.
Pro Reading flow
The characters have been designed to flow into each other so that the font feels easy to read.
Pro Distinction
Specific care has been put to make programming characters such as 1, i, and l or O or 0 easy to tell apart.
Pro Wider than usual
As it's wider, this means there's more space for designing characters like "m".
Cons

Con Pixelated
This is, of course, intentional; but it can be hard to look at compared to other smooth mono-space fonts.
Con Smallest font sizes hard to read
Fonts less than 11pt start to fail readability tests. 9pt specifically has an additional issue where brackets don't align.
Con Not really good in all font-sizes
Completely clean pixels, no anti-aliasing so its best viewed in (n*12) pixel size.
Bold font-weight is not really good because of small padding between them.
Con Not free
This font requires a purchase in order to be used. The cheapest version ('Basic') is 60 dollars. There is a free trial, though.
Con Wider than usual
As it's wider, this means a short adjustment period may be required. If you have a limited amount of horizontal space, the wider glyphs may be problematic as well.
