Buffy The Vampire Slayer
. (One heck of a rollercoaster ride. Can't think of a show that is better at defying exoectations.)
(great actors, some fantastic episodes).
Also, Terminator: The Sarah Connor Chronicles
. It's obviously handicapped due to the fact that Joss Whedon wasn't directly involved, but it does have Summer Glau providing comic relief (!!!) and Lena Headey as a great Sarah Connor. Could have been really special if it had made it to a third season.