It isn't neccessarily about heritage and consistency, flagship a lot of the time is an excercise in marketing.

GNE trumpet the Angel on the basis of the hybrid buses, the 7/8 frequency, wi-fi, next stop information and the fact it serves Durham, Angel and Newcastle. Probably the 3 key touristy areas of Tyne and Wear and that very busy Durham Road corridor.

They don't want you to remember the disaster of the Omnicities etc.

Was the 723 a flagship? I'd say it was in an age when a bus service was just a set of numbers and 4 wheels as opposed to a social media hub (perceived anyway) though its importance to GNE was probably diminished when it was joint op-d with United then Arriva before the dying days as a limited stop service alongside the 724 (disaster that was)