As a fan of ASoIaF books, I like the story of that best. But judging on the quality of the tv shows here, The Wire is by faaaaar the best - it has the best tv writing ever penned, and beautifully executed by everyone involved.
Followed by Breaking Bad which really has no weak points and got better as it went on which is remarkable for any show. But I feel the basic premise was just stretched too thin to fill the seasons and they kept on raising the stakes with some ridiculous plot elements. Still an A show, just not A+.
GoT surpasses expectations of a book adaptation to TV, and perhaps might be the best fantasy adaptation ever. I felt season 1 was its best, but it got weaker following that as they diverged further from the books. Its main flaws are due to the criminally short time dedicated to each book and how it creates awkwardly rushed editing. Very inconsistent in quality in each episode. First season - A, the rest B+ to B.