Sync favourites
Feature: I would like to be able to define a group for favourite (starred) entries so I can sync the favourite status to/from CardDAV.
Selecting one or more contacts and then being able to "mark (unmark) as favourite" would be nice as well.
Now modern Android systems have decent 'do not disturb' facilities, being able to sync favourites becomes more than a feature. Why? Because one of the handy do-not-disturb settings is to block phone calls from everyone unless the caller is marked favourite. Favourites are too important to leavy on the (vulnarable) mobile. A common approach is to use a contact group (or category) 'favourite' or 'starred' and have contacts from that group marked as favourite.