I started my digital reading on a kindle. I progressed onto Android tablets. I currently have a Samsung Galaxy Tab A 10.1. I also have Kindle Paperwhite, which I think is a third generation. My tablet is superior in every way, other than portability, battery life, and when you are in a bright environment where reflection off the tablet would be an issue like being outside.
I bought my mother a Kindle Fire and absolutely hate it. Every time I go to help her, there are tons of open spam windows. No access to the Google Play store prevents you from using common apps like gmail or chrome.
IMHO, a kindle is ok for just reading text. A Kindle Fire is ok if you want a tablet, but have a tight budget, just realize the limitations.
When it comes to the topic of this thread, some of the digital usefulness depends upon the formatting of a given volume. I have seen this with magazines. Some are great on tablets and some are little more than scanned images. I suspect the same could be true of non-fiction books, or a better way to differentiate might be mixed media books. Whatever you read needs to be designed for the format you are reading in.
If you shop at Costco, I recommend picking up a Samsung Tab A 10.1. They are frequently on sale for a little over $200. You have 90 days to try it out and return it if you don't like it. I love reading on mine.
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