For me it's been It's Always Sunny in Philadelphia. Can't get enough of it. I've been watching episodes by focusing mostly on just one character even if they are just in the shot and not talking and each of their facial expression and silent remarks, especially deVito's, are hilarious.
Futurama when it was on adult swim and The Simpsons when they syndicated the good episodes. I only cried twice when Fry's dog died.