The only problem I have with Kindle - it is an amazing device - is that I read a book recently that was filled with high definition color photos -
How We Got to Now by Steven Johnson. I don't think this would have worked on a small device either - I read this on my iPad Pro 11 and it was just about right - some images almost took the entire screen.
I am still stupidly on a quest to reduce my devices - so I gave away the iPad ... (it went to a very good cause - someone needed it far more than me). I then read a book on my iPhone 12 Pro Max
Can’t Hurt Me by David Goggins. The book was great, but the experience was not all that great. Constantly scrolling, even in horizontal mode, but grey text (brightness all the way down on black background) - did not hurt my eyes and I'm getting used to it. But it was not an enjoyable experience (had to force myself to read >1 hour).
With my iPad Pro 11 I can sit down and read for 6 hours solid no strain, no pain, no fatigue.
Interesting points about Kindle Unlimited - the only thing that I don't like about it is, I took my "wish list" and out of 20 books, only 1-2 were on it.
There are indications that reading inverted (i.e. white text on black background) could help preventing myopia (
https://www.nature.com/articles/s41598-018-28904-x), so the answer is probably not as easy as black or white (pun intended ;-)).
How interesting. Last 3 years I've been reading mostly on a black background with white text with brightness turned down (almost looks like grey). I found this enabled me to read for long periods of time without strain. I'm severely nearsighted though - have been since I was a kid (I read books on a daily basis growing up).
Just upsets me to have a $1200 device I only use for reading books (mostly) when I've got an iPhone/MacBook Pro - feels like such a waste. Apple Books on the iPhone is so unpleasant with the massive margins and holding it - I just can't get used to it. I guess there are worse hobbies/additions (for example $20 pack of beer/52 weeks = $1040 a year).
I do keep coming back to the IPP11 for optimal reading - for me personally.
Really appreciate all the thoughts and comments - thanks!