@kyo I've been very happy with my Pocketbook Touch HD (the first version, though I *think* all of this is still true for the later versions, but make sure to check!).

You can just dump files on it via USB as mass storage, it takes a microSD card, it has various optional(!) network syncing features, does not require network to function, and does not advertise on your homescreen. It does also have a browser (which is again optional) and a somewhat jank RSS reader implementation.