We have an Ipad. It’s useful beyond surfing the web and reading books. My husband has taken notes on it, can do work/access his computer at work…
If you have kids it can be invaluable in keeping them busy when they need to sit quietly but are having trouble. You can access drawing games and pottery games for children, books, etc.
I don’t think you can have any of these features with the kindle or nook.
If you just want it for reading/learning, though, the above two may be enough.