Kul Tiras is the most thought out human kingdom in the game. Gilneas feels insignificant in comparison (I know, not a fair comparison) and the other kingdoms are a variation of Stormwind, which itself is your typical fantasy human society. Dalaran is otherwise good, but kind of tiny. Still undecided whether I like Suramar or Boralus more, but the honors may go to Boralus for being functional as well as asymmetric.
I'd give Zandalar the same honors if Zul'drak didn't exist. One of Kul Tiras's perks is that it inhabits the entire archipelago, where as the Zandalari empire only has Zuldazar, Nazmir being lost to savages and Vol'dun being ignored. Zuldazar is fine, but I find Zul'drak grander, even as the Drakkari have fallen.
Regardless how one feels about the story, especially how it ended, we were treated some top quality cinematics. It was also a first for an expansion to feature more pre-rendered ones in addition to the intro (if we don't count the short with MoP's orc and human getting drunk in a bar).
Wrathion is miles better than he used to be. I liked him in MoP, but his model was kind of dopey. Now he has the looks to complement his personality. In fact I feel BFA did quite well with character designs. Bwonsamdi, Jaina, Saurfang, Anduin's armored version, the new Thrall, Kul Tirans in general, I liked the lot of them. Not Talanji though, her outfit looks awkward.
Other than that it's tough to say what BFA did better. It did well enough with many things, but I wouldn't say it was the best at those things.