I'm kinda late, I guess, but I thought I'd add my 4¢:

It's not experience, so much as accomodating the repetetivity of software development. Just like getting a better chair or a more comfortable keyboard, one day you find a font that strains your eyes and brain less than the last one, and you switch, and your eyes last longer.

Speaking of which, my absolute first reaction after I loaded that screenshot was "ouch, blur!" - to me, the combination of font, color scheme and antialiasing is making the text quite hard to read. Now, your eyes might be good enough to counteract that, and your screen might be lit differently from mine perhaps as well, making this reaction moot. On the other hand, if you look at some of the sharper screenshots in this thread (curl -s https://qht.co/item?id=10140728 | grep -o '<a href="https\?:&#x2F;&#x2F;[^"]\+"' | sed $'s/^.\{9\}//;s/.$//;s/\&#x2F;/\//g;/imgur\|png/s/[^$]\+/\033[7m&\033[0m/'), and your eyes go "...oooh.", then you might be blind to the blurriness of your font. You might adjust this by changing the font, your editor color scheme, or learning about FreeType (ahaha) and how to adjust hinting.

All of this is just technical blathering though; I'm not questioning your choice of font for the choice's sake, or criticising it. I'm just saying, in case you don't realize, I thought it was blurry with my eyes, on my system. :P

As for actually going about making changes and adjustments, this is usually done in the traditional manner - spending an afternoon avoiding the todo list and for example getting horribly distracted with color scheme designers or font comparison utilities or text editor build systems... ;)

You grab a bunch of fonts, try all the monospace ones, find one you like, and go with it.

I use Liberation Mono everywhere. You might want to give Oxygen-Mono a shot just for kicks since its the "kde" font, but having used both I still like my Liberation.

Your font is fine. Use whatever you like. Main thing I look for is fonts that differentiate between things like 0Oo and lI1. I prefer open source fonts too. Just don't use a non-monospaced font.

In my day we wrote Pascal in 9-point Geneva and we liked it! ;)

In THINK Pascal? In all those years I've never found another IDE that was as productive as this gem.

Yes! And same--the THINK IDEs spoiled me.

But it's so much easier to get your mixed tabs and spaces aligned correctly with a non-monospaced font!

You can get used to any font, and it is after all a matter of taste. I have preference but it's totally personal and might just be a habit. Whatever works, you know.