I'd argue we are in the golden age of television right now. Tons of good stuff. I did like The Americans, but something about the final season just didn't work for me.And really, it's kind of amazing how many Pantheon-level shows have finished up just in the past 5 years. I'm not as sold on Halt and Catch Fire, but Leftovers, Rectify, and the Americans are all right up there.
I'd toss in Watchmen and at least and honorable mention for Pillars of the Earth, but for some reason single series are ruled out because of Firefly