Boardwalk Empire is right up there with the best.
I don't know if it's top 10, but we're totally into Orphan Black on BBC America. And speaking of BBC America, I'm also digging Copper, which recently started its second season. Vikings was also great, hope that comes back next year. Mad Men seemed like it came and went in a few weeks. All of the series are too short these days, but I guess that's just the way TV works now.
The new show that airs right after Dexter on HBO, Ray Donovan is excellent so far, and it just got started.
But they are all just appetizers for season six of Sons of Anarchy which starts up again in September.