I'm considering a Long-Lived Favorite to be a show that went past two complete seasons (or is about to, such as "Chuck" which will air season 3 in 2010). Short-Lived Favorites will be shows that lasted two complete seasons or less but have already finished their run. Current Honorable Mentions are shows that just started, are renewed for a forthcoming 2nd season, or are in the middle of their 2nd season.
And, to be on the list of long-lived favorites for the decade, at least half the run had to take place in & after the year 2000. "Ally McBeal" just barely squeaks by, riding the fence between the '90s & 2000s. And, it ranks in the middle with it's best season (4) and worst season (5) both taking place in the 2000s. "Buffy: The Vampire Slayer" ranks lower because its best season (5) but also two worst seasons (6 & 7) take place in the 2000s. The season 6 finale and almost all of season 7 of "Gilmore Girls" were a travesty too, but its first 5.75 excellent seasons take place all in the 2000s, so it still ranks very high. Had it not been for the very last scene of that season 6 finale and subsequent unevenness of season 7, "Gilmore Girls" could have been at least two ranks higher.
And, oh yeah, I don't get premium channels, so no Sopranos, True Blood, etc. Sorry, but it's my list.
Top 25 Favorite Long-Lived TV Shows from 2000 - 2009
25. Rescue Me (2004 - current)
24. Last Comic Standing (2003 - 2008)
22. (tie) Brothers & Sisters (2006 - current)
22. (tie) Prison Break (2005 - 2009)
20. (tie) Beauty & the Geek (2005 - 2008)
20. (tie) Mythbusters (2003 - current)
19. The Daily Show With Jon Stewart (1999 - current)
18. Survivor (2000 - current)
16. (tie) South Park (1997 - current)
16. (tie) Buffy: The Vampire Slayer (1997 - 2003)
15. The O.C. (2003 - 2007)
14. Scrubs (2001 - current)
13. Ally McBeal (1997 - 2002)
11. (tie) The 4400 (2004 - 2007)
11. (tie) Chuck (2007 - current)
10. The Shield (2002 - 2008)
09. Boston Legal (2004 - 2008)
08. Stargate: Atlantis (2004 - 2009)
07. Battlestar Galactica (2004 - 2009)
06. House (2004 - current)
05. Gilmore Girls (2000 - 2007)
04. Stargate: SG-1 (1997 - 2007)
03. The Practice (1997 - 2004)
02. The West Wing (1999 - 2006)
01. Lost (2004 - current)
Top 15 Favorite Short-Lived TV Shows from 2000 - 2009
15. Kid Nation (2007, 13 episodes)
14. The Jeff Dunham Show (2009, 6 episodes)
13. Who Wants to Be a Superhero (2006 - 2007, two seasons, 14 episodes)
12. New Amsterdam (2008, 8 episodes)
11. Women's Murder Club (2007 - 2008, 13 episodes)
10. Kings (2009, 13 episodes)
08. (tie) John Doe (2002 - 2003, 21 episodes)
08. (tie) Defying Gravity (2009, 13 episodes)
07. Terminator: The Sarah Connor Chronicles (2008 - 2009, two seasons, 31 eps)
04. (tie) Standoff (2006 - 2007, 18 episodes)
04. (tie) Journeyman (2007, 13 episodes)
04. (tie) Moonlight (2007 - 2008, 16 episodes)
03. Men In Trees (2006 - 2008, two seasons, 36 episodes)
02. Jericho (2006 - 2008, two seasons, 29 episodes)
01. Firefly (2002, 14 episodes -- 3 of those never aired, found on DVD only)
Current Honorable Mentions
- Cougar Town
- FlashForward
- Glee
- Sanctuary
- Star Wars: The Clone Wars
- Stargate: Universe
- V
- Warehouse 13
So, what are your favorite TV shows of the decade???