This is the best of all time so i get to reflect on my childhood... Yay!
1. Teen Titans- BEST SHOW EVER. IT HAS SLADE WILSON IN IT. PERIOD. I'm actually really surprised that has not been mentioned more on here. And not the new crap i mean the old classic stuff. They just don't make them like they used too.
2. Family Guy- always have liked it; always will
3. Arrow- I'm starting to really get into it and am excited for season 2.
Honorable Mentions: Batman the animated series. Star Wars the Clone wars. Spectacular Spiderman. The Most Extreme. Deadliest Warrior. Super Hero Squad Show ( that was good when I was 7 or whatever but now not so much), Spongebob ( come on everyone did at some point), Justice League, Justice League Unlimited, Young Justice.
You ask an impossible question. All I can say with any certainty is The Wire and IT Crowd. Third place is a tie between quite a few shows; Ren and Stimpy, 21 Jump Street, Columbo, Kung Fu, Walker Texas Ranger, Deadwood, Frisky Dingo, X-Men (90's series), Seinfeld, Wonder Years, and a bunch of other shows.