Also, how does someone measure a great TV series?

Some TV series had only 1 season or a series of episodes over years that never officially became a season but a considered sublime (e.g. Fawlty Towers). Some have multiple seasons that are not connected but each a contained piece (e.g. Blackadder).

Some have lasted over 50 years and still keep going, some are watched by more people than others, some never get an audience and disappear. Some are on 5 days a week, and have thousands of episodes. Many have amazing starts but never know when to end, X-Files anyone?

But, on the basis of comparisons to GoT, a story led, multi-episode arc based series. I'd say Buffy was in contention, even if the first 3 series were it's peak. STNG certainly, even if the first 3 seasons were a bit weak.

However the series which started well, continued strongly, ended utterly sublimely and is still talked about and analysed today. Had moments of quiet, story, action, love, hate, everything, it knew when it was ahead and when to get out, never overstaying it's welcome...The Sopranos would probably be the greatest tv series ever imo.

As for the GoT episode, it may have been the best action episode of the series, but best episode? Not a lot was said to qualify it for that.