From my childhood
Ed, Edd and Eddy. Let's put it this way, I can still quote it as a grown adult to a friend of mine or to my sister and we still find it funny.
Teen Titans, the TV show. I am not even into superhero stuff, but I just really liked the stories and the characters. I especially liked Raven, which I am sure had nothing to do with my "Goth phase" when younger.
Overall
Invader Zim. Typical Jhonen Vasquez insanity. It's pretty much the epitome of the once overused word "random". It's strange for the sake of being strange, incredibly over the top and I love the art design and characters.
Anime
Puella Magi Madoka Magica. The art style is gorgeous, the story is excellent and moving, and it's very intelligently made. It's also not what you'd expect if you looked at it's cover art, it's just amazing.
Mardock Scramble. I have only seen part one of three as the other two are not out yet, but something about it has me hooked. I loved the style, the cyberpunk setting and it's complex story. It's surprisingly unknown.
Darker Than Black Season 1. One of the first anime's I ever watched and I still love it. The characters are excellent, the plot is interesting and it's a great mixture of action with a light touch of humour without it being distracting.
Ghost in the Shell Stand Alone Complex. I love cyberpunk, I love anime with a more serious tone and with a compelling and believable story. The characters are brilliant, the pacing is very well done and it also has some of the best OST's I have ever heard.
Others that I won't go into why or I'd be here all day, in no particular order are Code Geass, The Melancholy of Haruhi Suzumiya, Elfen Lied, Fullmetal Alchemist Brotherhood, Neon Genesis Evangelion, K-On!, Angel Beats! and Ergo Proxy.