Please note that most of my picks will be of animated variety, either anime or Cartoonnetwork (before it became shite), because that's how I roll.
Animated: Yu Yu Hakusho - I love this show. It's simply everything I could want. Action, comedy, animation, story, interesting and likable characters, intimidating and powerful villains, exc. This show simply rocked my world and had so many characters that meshed so well together and created such a fantastic atmosphere that I find it hard to pick anything else as my favorite Animated TV show ever.
Kuwabara: "I'm supposed to get strong from seeing him get hurt, hit new levels! It's the part where I power up and save the day! No! We've survived too much... learned too much to let it end this way!"
Comedy: Megas XLR - The crown jewel of CN, this show was hilarious and a blast to watch. With funny lines spewing from everywhere (Especially Coop's companion Jamie, voiced by the great Steven Blum), this show would have you laughing from beginning to end. Not to mention it had some fantastic music, animation, and action sequences, but I always remembered it just for its fantastic sense of humor.
Coop: "I've killed bigger before."
Jamie: "No you haven't! The thing's a flippin' PLANET!"
Drama: Cowboy Bebop - I sort of disqualified YYH to win this, since I already picked it for best animated, and while Bebop was just recently discovered by me, I thought it was fantastic. It was dark, funny, edgy, action packed, full of mystery, and overall a fantastic show. Not to mention that the ending was a shock of epic proportions (Which would have been more of a shock, had spoilers of its end not been spilling out of every end of the internet), which left you wanting more, but knowing that there was nothing left to be said. Not to mention, it spawned one of the most used ending lines ever:
Spike Spiegel (Cowboy Bebop): "Bang."
Yusuke Urameshi (Yu Yu Hakusho): "Bang!"
Kei Kurono (Gantz): "Bang!" [Incidentally, this was a great Drama Anime too.]
TOM4 (Toonami): "Bang."