DAVx5★★★★★Background app that syncs your non-Google cloud accounts with your Android system calendars and contacts.
Feedly★★★☆☆Cloud-based feed reader with all the bells and whistles, focusing too much on the bells and whistles.
Floccus Bookmarks Sync★★★★★Very flexible, syncs across many different desktop browsers and mobile devices, and for privacy it can run on your own server or encrypted on another cloud service.
Nextcloud News★★★★★Simple web-based news reader for Nextcloud, easy to install and syncs with mobile clients.
Nextcloud Notes★★★★★Simpler than Google Keep, more private, with human-readable data that syncs quickly and cleanly with your devices.