I've found that Tom and Jerry is probably the greatest cartoon of all time. Simply because it's something my entire family watches. My dad (for instance) loves it. I remember watching Cartoon Network every New Year's Day because they used to run a massive Tom & Jerry marathon on that day.
IMO: Nothing beats the Transformers cartoon. I'd make a "you got the touch" joke here, but Mark Wahlberg beat me to it.
Or the Real Ghostbusters. I didn't know until recently that JMS wrote a lot of episodes for that series.