I have Sopranos, The Wire and Six Feet Under in my top 5 too. Also Seinfeld and then a it's a toss-up between Mad Men and West Wing for me. I love GoT, but don't really think it's up there with the greatest in terms of quality. More of a guilty pleasure - liberal amounts of dragons, sword fights and boobs will always be entertaining.
Right now the other shows I'm watching that I really like are Billions and Better Things. Really different shows, but both have great soundtracks.
If that is a winning formula I am going to get to work on a new screenplay about a tourist that stumbles into Happy Hinomaru and has to fight his way out.