For your list (battery life, organize in Calibre, Overdrive, epub), I'd still recommend a Kobo. A Libra. Maybe a Forma.
You mentioned not liking Kobo's UI. Not sure when you last used it, but there have been some changes just in the last couple of firmware updates. Not sure if these would make the UI better or worse for you. But at least KOReader is always an option if it still doesn't appeal.
|