I am not sure I understand your desire to try a new, longer routing just to try a new Y cabin/routing/airline.
All Y is fairly similar, and BA is above average. Especially with your BA status, I see no real reason to make your trip take hours longer.
If we were talking J or F flights, I think it would be a lot more fun to try a new airline, but with Y just stick to BA non-stop.
(UA or VS non-stop would be decent alternatives, but not OW)