You might possibly be interested in checking out the YouTube channel MyDeepGuide. Guy does in-depth reviews ofbmostly e-ink writing tablets, which perhaps is more functionality than you're looking for, but some of those manufacturers also do standalone "just" readers. Or maybe you'll be convinced to get a writing tablet :p
Books
Book reader community.
i have a kobo libra 2 and it's served me very well. I sail the high seas for most of my books and I haven't had any issues at all loading content onto it, it's always fast and responsive, and I cannot understate how nice having physical page turn buttons is. highly recommend if you can find one, though theyve been mostly discontinued to make room for the color model that came out recently (would not recommend the color version, color e-ink is very hit or miss right now and it's not worth the screen quality trade-off).
I have used PocketBook touch lux 5 but the screen cracked twice. (User error but still, screen is a weak link)
KoReader made it so snapy I couldn't believe it at first.
Now I have got kindle as I received it as a gift, so I jailbroke it and also installed KoReader on it.