The Sopranos was good but the writing could have been better and some of the acting stunk. It was ground breaking for its subject matter, much like the Godfather movies.
In my opinion, The Wire should be near or at the top of this list. I didn't care for the way the series ended, but that doesn't negate the superb storylines, writing and acting throughout its run.
Currently, Breaking Bad is making a run for top drama, even outpacing Mad Men and Damages.