Quoted By:
What I loved about B/W was that it had a coming-of-age story that actually involved the protagonist. Both them and rivals start out the journey to have fun with friends and,as they meet gym leaders and other characters their different views of the world brush off on them.
As the plot progresses Cheren's strong view of his future and values clash with those of Alder and Clay for example,and he eventually loses his security and starts reevaluating his views,but that only makes him stronger and more confident in the end. Likewise Bianca starts off without much confidence and without clear direction,but encountering Elesa and Juniper,she learns to be more self-confident and take life one day at the time.
And then we have protagonist. Unlike in previous games,they aren't a badass kid who wants to be the champion with no characterization while they rivals develop. This time,they started their journey for fun,but changed their goals once their started winning gym battles. However then,by the end of the game they realize thee is a much bigger issue at hand that overshadows own personal plans and go fight to protect their world instead.
There is also a coming-of-age story built around N,who,with a stolen childhood,and later shattered world,strives to be the king of Unova,childishly clinging to his own ideals,only to return in BW2 as it's protector.
The message that spanned across the whole generation was to accept diversity and that there isn't a right worldview. The whole castle part with gym leaders uniting with a common goal and N thanking protagonist illustrates it the best.
tl;dr: B/W had the best story in the series.
