The Wire is in a class by itself for me. The Sopranos first 2 season were on par, but quickly fell off.
I would go in this order for myself when looking at the overall series and not just individual seasons....
The Wire
West Wing
Breaking bad
Sopranos
Mad Men
Then a drop off to
Shield
Oz
Sons Of Anarchy
Dexter
I really enjoyed Rome, but was not on long enough
Shows that I think have a chance to be really good running currently are:
Newsroom ( think this is great, but I really like Sorkin)
Boss
Magic City
Homeland
I enjoy the shit out of House of lies in the same way I loved Entourage