I've been reading pirated books on my Kindle. Kindle for the hardware, library genesis for the books. I buy the books that I enjoyed, After reading them.
Although my book sources are messed up, you can also read your legitimately bought .epub books on a kindle. Your question, "which e-reader", isn't the right question I think. The question should be, from where are you buying the books legally.
I wonder if I'm getting banned for advocating piracy.. Let me check the rules and stuff..