Sansa's evolution was the best delivered, likely because it was based on the life of Queen Elizabeth I (the writers did much better with a clear template to follow than creating their own). Many seem to believe that because she was utterly naive and ambitious, she almost deserved to be abused, but while I was never fond of her character, I certainly respected how she learned and grew and manipulated, navigating dangerous circumstances and working with what she had, in order to survive, and somehow managing to not lose sight of both the small and big picture. Her storyline felt the truest from beginning to end.
I thought the deaths of Cersei and Jaime, although poorly arranged to occur, were poignantly perfect for that screwed up relationship and there was a sense of rightness to Tyrion discovering their (ludicrously undisfigured, but I digress) bodies as he did.
Now, for the most erroneous negatives (I'd be up all night if I wanted to gripe about every one).
Euron and the crossbows. Cartoon character villain Euron and the fricking giant crossbows. Oh hey, need a dead dragon for plot purposes? Let's have everybody forget that these weapons exist and then miraculously remember that they have significant maneuverability limitations. Rubbish, the lot of it, and I don't know how any person with half a brain cell didn't shoot the idiotic idea down during conception, much less continue to support it until it reached the screen.
The decision making process of naming Bran the king was bafflingly and stupidly horrible, as well. That, and the assembly of the council, was like a fever dream straight out of a fan convention gathering, where all your favorite actors congregate and ad-lib a few lines on cue for the audience. None of that part of the script appeared to have been given any critical assessment. It was senseless, unrealistic, and completely asinine, enough so that I was confused for a bit and wondered if I had started hallucinating a gradeschool-level, novice writer's take on the show.
But where I believe there had been the greatest potential, which was squandered and failed at miserably, was the tale of Jon and Daenerys. It could have had the emotional impact of a two-ton sledgehammer, but they never had the faintest resemblance of chemistry, despite both performing their hearts out. They were thrown together to suit the story's direction, relying on our bird's eye witness of their separate journeys to foster it along. There was not a single moment when I was even briefly fooled into thinking these two pretty people had genuine love for one another, and the stabby scene had not an ounce of the sentimental value that Drogon's nuzzling did.