At this point I'm not going to advocate for moving from 10 to 11 since people don't seem to like it. However the default fixed-width font is Hack 9. I don't see any reason for the default fixed width font to be smaller than the default general UI font. And to my eyes, 9 it just too small to be comfortable in Kate and Konsole--the kinds of apps that used fixed-width fonts that typically have very dense text display.
So I'd like to propose raising the default font size for fixed-width fonts from 9 to 10:
Kate, Hack 9:
Kate, Hack 10:
Konsole, Hack 9:
Konsole: Hack 10:
With a non-HiDPI screen, 10 also looks a bit sharper than 9 to me.
If people agree, this would need to be done in the Fonts KCM, in Kate, and in Konsole.
What say ye?