You first need to think about where you'll be getting your eBooks from. If you're planning on downloading titles from your local library service, you should check which devices are compatible with the formats that they use. For example, eBooks borrowed from the library service here in Suffolk are compatible with Amazon Fire tablets, Android tablets, iOS tablets, Nook and Kobo eReaders but NOT with Kindles:
https://www.suffolklibraries.co.uk/services/overdrive
So you shouldn't buy ANY type of Kindle if you're planning on getting most of your eBooks from a local library service which operates in the same way that the one in Suffolk does.
However, assuming that you do want to purchase a Kindle, the main review sites (such as Tom's Guide, TechRadar and PC Mag) all seem to agree that the Amazon Kindle Paperwhite is the best buy overall (primarily because of the quality of the screen, which closely mimics a printed book) but that the regular Amazon Kindle is still a decent buy for those on a budget. e.g.
https://www.techradar.com/uk/news/best-kindle