When comparing Inconsolata-g vs Proggy Clean, the Slant community recommends Inconsolata-g for most people. In the question“What are the best programming fonts?” Inconsolata-g is ranked 5th while Proggy Clean is ranked 42nd. The most important reason people chose Inconsolata-g is:
Inconsolata-g has been released under the SIL Open Font License 1.1.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Free and open source
Inconsolata-g has been released under the SIL Open Font License 1.1.
Pro Fixes clashing of similar characters
Inconsolata-g is a variant of the popular Inconsolata that fixes the similarity between "1" [one] and the "l" [lowercase ell].
Pro Great scalability
Inconsolata mantains its legibility even with small font sizes.
Pro Line height is a little larger than normal
This makes the lines feel less crowded which greatly helps readability.
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.
Cons
Con No Italics
To improve contrast, italics are best used for comments.
Con () and {} are difficult to distinguish
The user may have difficulty distinguishing small size () and {} at a glance.
Con No pretty ligatures
Ligatures are nice-to-have in languages such as Swift.
Con Looks too small next to other fonts
Con Character widths are not consistent between regular and bold
Bold characters are not the same width as regular characters so the typeface is not consistently monospace.
Con Dotted zero
Dotted zero is less readable than slashed zero.
Con Looks significantly worse on Windows (ClearType)
Con Renders lines as dashes in TUI interfaces
Lines in items like midnight commander, the treeview in htop, tmux panes, the tree command, et al., have ugly dashed lines instead of straight lines with sharp corners.
Con Requires more work than Inconsolata to install on several OS's
Because Inconsolata is in the package managers for almost all open source OS's, it is much easier to install than Inconsolata-g in most cases.

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.
