I have a Boox Palma, which is an android ereader.

For me the form factor is great for commuting and brining to things like sporting events, as it can just got in my pocket. Also, since it runs android I can load any apps I want, letting me use my self hosted eBook library (Audiobookshelf) and access to things like music or sudoku.

Edit: Also the battery is still pretty great, since phones use most of the battery for the screen.