These are the 10 Highest Rated I could find:
Game Of Thrones
IMDb - 9.5/10
TV.Com - 8.8/10
Metacritic - 79/100
Overall - 8.73/10
Dexter
IMDb - 9.3/10
TV.Com - 9.1/10
Metacritic - 77/100
Overall - 8.7/10
Boardwalk Empire
IMDb - 8.9/10
TV.Com - 8.3/10
Metacritic - 88/100
Overall - 8.66/10
The Walking Dead
IMDb - 8.9/10
TV.Com - 8.7/10
Metacritic - 82/100
Overall - 8.6/10
Breaking Bad
IMDb - 9.2/10
TV.Com - 8.9/10
Metacritic - 74/100
Overall - 8.5/10
Mad Men
IMDb - 9.0/10
TV.Com - 8.8/10
Metacritic - 77/100
Overall - 8.5/10
Justified
IMDb - 8.9/10
TV.Com - 8.0/10
Metacritic - 81/100
Overall - 8.33/10
Californication
IMDb - 8.7/10
TV.Com - 8.9/10
Metacritic - 70/100
Overall - 8.2/10
Fringe
IMDb - 8.7/10
TV.Com - 8.9/10
Metacritic - 67/100
Overall - 8.1/10
Sons Of Anarchy
IMDb - 8.8/10
TV.Com - 8.5/10
Metacritic - 68/100
Overall - 8.03/10
Others; The Mentalist - 7.83, Supernatural - 7.93, True Blood - 7.76, Spartacus - 7.66, The Vampire Diaries - 7.06