Anything I don't have to connect to some dumb ass account, and I can just plug into my mac and shove some theory onto it. I don't need wifi, or bluetooth or anything. Just a simple, dumb book device.
Honestly I love my Kindle. You don't need an Amazon account to sign in or anything, just disable wifi forever and you're golden. I load mine up with pirated ebooks using Calibre and it's great.
I put my Kindle into airplane mode the day I got it and I've never bought a single ebook in my life.
I've got a Kobo and use it offline with downloaded EPUBS, works great. I think you need to modify one file from the computer to use it without an account, though. If a Kindle works without an account or internet, they are cheaper used than Kobos. The main disadvantage is that Kindles can't read EPUB natively, you need to convert to MOBI or something.
Either way, I'd highly recommend getting a real e-reader over something with an LCD screen. It's way easier on the eyes and the battery lasts ~10× as long.
I just use my phone to read ebooks, but once you find a device message me and I can get you an invite to a private torrent tracker site just for books. Audiobooks, magazines too
Any cheap Android tablet will do as an e reader as well, I know Amazon's $50 one used to be rootable so you could install stock Android instead of their bloat but I dunno if you can on the current models anymore
