I have a Nook Simple Touch with light. It's kind of old these days, but quite satisfactory. I'll be unlikely to replace it until it breaks.
My main reason for going with this reader was that it was an Android and could be rooted. In practice, I've found this feature to be of only sporadic use, typically when traveling without other devices. The web browsing is not ideal, but it has proven extremely useful in a pinch. For day-to-day use, apart from reading I only ever used a flashcard app, which was fantastic for my commute. It's technically possible but difficult to get a keyboard hooked up via USB; I never bothered.
I have no idea about the modern e-ink Nook they have out, other than that it also runs Android and can be rooted. I also don't know if that one has the extra feature I'd like most: to be able to use additional dictionaries (my reader is limited to the stock one).