I second Boox as a decent option (though less polished.) Allowed me to get rid of my dumbass Kindle and Kobo dual set up because if there was a book that was exclusively on the Kindle store I can now just get it in the app rather than owning a whole other ereader. The only thing I don't like about it is it is not as good as either Kobo or Kindle for dictionary lookups. This is especially important to me because I read in foreign languages and need it to be able to either give me a definition or translate it no matter how it's conjugated. I have found the Kindle app for Android though works pretty well for that purpose so there is an ok solution.