Could you bring back the shortcut/nickname functionality to Opera.
It's easier to write a shortcut in the address bar than searching in the bookmarks folders when you have many bookmarks and/or several bookmarks on the same website.
It saves a lot of time when you use your browser daily.
It's also easier to open a bookmark with shortcuts than searching it using predictive input in the address bar based on your history/bookmarks when you visited different websites with similar address (for example weather websites), or if you have several pages of history on the same website.
Opera 12 had it, and other browsers use it (e.g. Firefox, Vivaldi), it was one the the few functionalities I used very often on opera 12 (with Mouse gestures and Opera lync which are already implemented in opera 30)