1. Sopranos
2. Six Feet Under
3. Oz
4. Curb Your Enthusiasm
5. Dexter (First 1.5 Seasons??)
My top 3 could all be my #1. Sopranos never seems to grow old with me, though. Lately, though, I have been catching Oz on HBO at 11 PM, and I forgot what an incredible show it was.
Six Feet Under: I can't even watch this show anymore because it's too nostalgic. (Wonder Years comes to mind in this comparison)