For me it's the ability to read outside in bright days, so I can take care of kids in the beach/pool.

I went for a boox since it's an Android and can run not only my favorite e reader app but also dictionary, browser for Wikipedia, and any apps for Android such as news Guardian, DW etc.

Obviously it also runs official apps such as Kobo, kindle etc, so I can try/ buy the book wherever and later I de DRM it and upload epub.

Oh also I have severe dust allergy from physical books, and moved countries a couple times leaving behind lots of unread stuff.