Because it is. It's awesome. And wonderful. And generally perfect.
...of course there's also the tiny matter of Buffy the Vampire Slayer being my favourite show ever. And Farscape. And also Frasier, and Avatar: the Last Airbender, NCIS, Tru Calling, Newsradio, and Firefly.
But RIGHT NOW TODAY, Sarah Connor Chronicles is my favourite show ever. And will remain so for at least the next ten minutes.