For my eyes black on white is far superior. White on black results in haloing around all text, whereas black on white results in generally pretty crisp text. This is why I use light themes and high-contrast mode for anything that supports it. (The glaring exception is Spotify)
The basic idea is that for folks with blurred vision (not out of focus, literally blurred), bright colors will erode into dark surroundings. Dark text on light background means the text is uniformly slightly lighter than "ground truth", light text on dark background means a distracting halo forms around the text.
This. A thousand times. I'm an oldster -- and no, 40 is not old. My vision varies from dead sharp to blurry depending on eye fatigue, probably blood sugar levels, and how my rather large floaters are behaving. But by the end of a day of reading, it's almost guaranteed that my eyes will be blurry from fatigue and age-related stiffness, complicated by that modern-day miracle -- replacement lenses for cataracts. As a consequence, reading any light text on dark background when my eyes are blurry is just a mess of haloing. The haloing bleeds three or four lines above and below the line I am reading, creating a big fuzzy mess that's annoying and hard to read.
To be clear when I mention floaters, I don't mean the little black squigglies that everyone experiences at any age. Rather mine are more like floating but not completely un-anchored translucent blurs that move right when my eyes move left. I suspect mine are Weiss rings.
Know that all that time you spent choosing a font color that is one-level of gray removed from invisible ink will never be enjoyed by me. I've overridden the the default font and font color in my browser to be a nice large, heavy, mono-spaced black font. When my eyes are fresh, yeah, I can read your 300-weight pseudo-invisible ink just fine, but it flatly irritates me, hence the overrides. And right click inspect is my boon companion when reading any page too-trendily designed.
If you're less than 40, it's hard to appreciate how age changes one's eyes. So if you're a youngster, have a bit of sympathy for us old folks when choosing color schemes. Or don't. I'm happy you can do creative, and that those of us with less-than-youthful vision can make adjustments. Best of both worlds.
This is great insight, thank you for commenting. I'm very much interested in design that is at the intersection of accessible and beautiful at the same time. Unfortunately those things seem to be pretty mutually exclusive but it's my belief they don't have to be.
I always appreciate this sort of feedback - especially as a young guy! :)
Sounds like you have astigmatism. It can be mostly corrected by glasses.
But yes a dark on light theme helps a lot too! I like that almost all apps support light and dark modes these days so I can just switch to what I feel like. I have some astigmatism to but not very bad and I like the calm of a dark screen at night.
The basic idea is that for folks with blurred vision (not out of focus, literally blurred), bright colors will erode into dark surroundings. Dark text on light background means the text is uniformly slightly lighter than "ground truth", light text on dark background means a distracting halo forms around the text.