When comparing Input Mono vs Operator, the Slant community recommends Input Mono for most people. In the question“What are the best programming fonts?” Input Mono is ranked 44th while Operator is ranked 48th. The most important reason people chose Input Mono is:
Many letter-forms are available in Input Mono, the width and line-height of which are changeable. There are also non-monospaced sans and sans-serif forms available.
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Pros
Pro Customizable
Many letter-forms are available in Input Mono, the width and line-height of which are changeable. There are also non-monospaced sans and sans-serif forms available.
Pro Free for private use
Pro Great on small-sized, high-resolution screens
Input Mono is designed to look good on HiDPI and low-resolution screens of variable zoom levels.
Pro Large punctuation
The punctuation symbols are larger than in other traditional fonts, making for greater visibility.
Pro Non-monospaced sibling fonts
In addition to the monospaced variant, the Input family of fonts includes serif and non-serif proportional font families.
Pro Has a script version
Operator can be used to mix the same font for syntax formatting.
Pro Super readable
Long strings can be read in Operator exceedingly easily. The font just flows nicely, with all the benefits of clarity that provides.
Pro Horizontal width not as wide as other fixed width fonts
You can legibly read everything and get more characters per line.
Pro Adorable italics
Cons

Con Relatively expensive
At $179, this font is on the more expensive side.