It's an absolutely fantastic show, the funniest ensemble comedy I've ever seen that incorporates some real emotional scenes beautifully. Seriously, if you've never seen it look the show up, the first season starts off a little slow since it's a very character driven show, but after a few episodes you'll be hooked.
1. Life on Mars 2. Breaking Bad 3. Sherlock 4. Doctor Who (classic series-not new!) 5. The Inbetweeners
Others which I considered and would shortly follow on a slightly longer list; Only Fools and Horses, Blackadder, The IT Crowd, Minder, Fawlty Towers, Ashes to Ashes.
honorable mentions: Curb Your Enthusiasm House seasons 1 & 2 (after that it really went downhill) LOST season 1 only (ditto above) Millennium X-Files seasons 1-6 Angel Kids in the Hall
Too many to choose from Had to do a top 10 in no particular order: Friends, How i met your mother, two and a half men (sheen), inbetweeners, the o.c, entourage, game of thrones, suits, THE BIG BANG THEORY, scrubs
Breaking Bad Dexter Chuck Sherlock Arrested Development
In no particular order, and keeping in mind that I have not seen greats such as The Wire, The Sopranos, The Shield, Game of Thrones, and more, of course.