Going on the assumption of "3 current fave shows" and not 'of all time', for me it'd have to be:
House Big Bang Theory The Mentalist
CSI:Las Vegas used to be another but with Grissom gone (and the other changes) I don't watch it often anymore. I liked Glee for the first season but the second season has been "meh." Loved HBO's Rome, wish they could've made a 3rd season.
Overall I don't watch much series TV...I tend to forget to keep up with episodes and thus lose interest quickly.