Kobo is more open and is price competitively with Kindle. It's also much more customizable if you are into that.
There are also a lot of Android e-ink tablet like BOOX. These are more expensive but a much, much more customizable as it's basically an Android reader.
Contrast shouldn't be a problem with any recent device. But anything release in past 1-2 years are excellent.
Seems like no matter how good the display and build quality, all eBook readers are bound to stop holding a charge after 3-4 years. I feel like the ongoing availability of newly-produced replacement batteries and the difficulty of replacing them are the primary factors in choosing an ebook reader.
My 2015 Paperwhite barely lasts 20 minutes after I pull the charging cable, even back in 2018 it was down from two weeks to two days per charge.
It's not like you can avoid the problem by loading up on extra batteries. A replacement battery manufactured shortly after the reader is going to be as bad as the one that came installed by the time I need it.
All the other problems I worry about like responsiveness, display quality and defects apply early on when a refund or warranty replacement is a solution.
I don't think any e-readers are designed to be user-replaceable except the very first Kindle. As for DIY replacement, I don't really know, sorry.
> A replacement battery manufactured shortly after the reader is going to be as bad as the one that came installed by the time I need it.
Is it? I was under impression that battery mostly degrade with cycle count. At least, there are plenty of people still use Kindle from 10 years ago.
> [...] warranty replacement is a solution.
Then I think you are mostly limited to Kindle or Kobo. Most other e-reader or e-ink tablet are mostly shipped from China so warranty and replacement are going to not be as good.
You must have had a heavy use of your kindle. Even if the battery is not new they consume so little that I am not having any problems.
Having said that, every electronic should have user replaceable batteries instead of being a programmed obsolescence nightmare.
I have a Pocketbook HD3 Touch, and really like it. It's a 6" monochrome model, with white-to-red-tint backlight. Previously I owned their 360 model - with a clip-on cover and at 5" size, it was perfect to slip into a jacket pocket for bag-less outings. Sadly ebooks in that size are rare now.
Pocketbook are known for supporting lots of formats of ebooks, and being 'pretty open', but your expectations will vary there, I'm sure. They did bring out a similarly sized colour eink model about 2 years ago which looked tempting, though I personally don't have much material in that size that'd benefit from colour, and moving around text book, let alone A4 sized material on a 6" screen would be awful.
If you want to run android apps then check out Boox. I immediately bought one after playing around with one in person. But that's more of a tablet that can be used for reading than just an ereader.
Being able to own my books outright is the only reason I went with Kindle over Kobo in 2014.
For those who want to try this at home, you're looking for the Calibre Obok Plugin. I think it's usually part of the DeDRM package which you probably already have. I can't remember where I found instructions but this page seems more or less accurate:
https://www.epubor.com/calibre-kobo-drm-removal-plugin-obokp...
There is one simpler way of accomplishing the same thing: just go to LibGen and look for the book you bought. And download a fresh copy from there. That might be the best solution.
Okay, relevant to the discussions of e-reader formats: Why, on my 2014 kindle, do MOBI files converted from ePub not support all the fonts on my Kindle? A native purchase, or even at times a non-native MOBI direct, looks better than an epub->mobi conversion. I had to create a new preset on the Kindle for font and margin to make it look tolerable.