Who am I to create such a list? The guy who runs this blog. That's who.
5. The Sopranos - I've told anyone that will listen (and lot's that would have preferred not to) that Tony Soprano was for me the most fully realized fictional character of all-time (until he was surpassed by a certain Old West bartender). Tony is a bad guy. He does terrible things, to good people (and a lot of terrible people too), and yet at almost every turn, you understand why he's doing it. You don't agree, or support, but you understand. He's not a charicature of a gangster. He's what one imagines the real thing is like. For that alone, this show would have to make the list.
4. Arrested Development - This show was literally too funny for television. It was too good to last, and so it didn't. The good news is, since it died early every episode is as good as the first. The creative juices never ran out for this series, which bodes well for the rumored big screen version.
3. The West Wing - A show that started off promising, became transcendent and ended great. Characters came and went (often without proper explanation, Thanks Sorkin!), the creator even took his ball and went home (so to speak) but still, Jed Bartlett and his administration steered the (imaginary) country for eight years. Seven glorious seasons of high-quality character development and issue-oriented storylines. This is how you do politics on TV.
2. Lost - It may not be fair to hang the "greatest ever" tag on this show since it's not done, and could (theoretically) come off the rails in the last 24 or so episodes. But we all know that's not going to happen. The finale of this show (I imagine) will become the kind of cultural zeitgeist water-cooler fodder that the finale of "Mash" and "St. Elsewhere's" have. People who've never seen the show will get the jokes made about it because they will be everywhere. Every few years, a new fanbase explosion will happen as people find the show on DVD and ponder the mysteries of the Island.
1. Deadwood - Vulgar, Violent and very very good. This is not only the greatest television show ever created, but one of the best entries into the western genre as well. A genre that you already know I love. There is no "main" character, but the show centers on Al Swearingen (the aforementioned Old West bartender) and Seth Bullock (a once and future lawman). Historical characters are blended with fictional characters into semi-historical scenes and it is tremendous. If you can get past the language (and there's a lot of it) this show is worth its weight in gold.