I have only had kindles so I don’t have anything to compare to. But I love them. The paper white is the best balance for features vs money. I have an oasis now and I feel like I just paid more money for nearly the same thing. I don’t like being stuck with amazons book store. But it does have most of the books if ever want to read. Classic books can be a lot cheaper or free. It hurts to pay more than like $8 or $9 for a digital book, but I will confess that I do it anyway if I want the book badly enough. After all, I get many, many hours of entertainment from it. In my limited experience with uncommon books, if it is uncommon in printed form then it probably isn’t on the Amazon kindle book store. Obviously that depends on the book. I have sent PDFs to my kindle before and it was fairly easy, but I’ve never had to do it often. I don’t know if other competitors do this, but one complaint is that you can’t zoom on a picture. For example, many fantasy books have a map in the beginning, and depending on the map, you might not be able to read much of it.
I’m not sure if it’s the wildest but the first that comes to mind is “John Dies at the End”