The AV Club, steadily unveiling its best of the '00s, has generated a massive list for the best TV series. There are no runners-up, only winners.
I note with pride and a little sadness that I have seen, in their entirety, half of the acclaimed shows, including 8 of the top 10. (I let my wife carry the Lost burden, and The Shield is on my queue.)
Of course, there's no spoiler in noting that The Wire is #1.