I used to watch a lot of Cartoons when I was a kid, my favorites being:
-Edd, Ed, 'n' Eddy
-Courage The Cowardly Dog
-Batman: The Animated Series
-Star Wars: Clone Wars (Not the new one with the Mary Sue Apprentice)
When these shows were taken off Cartoon Network and were being replaced by Adventure Time, Chowder, Flapjack, and the Regular Show I pretty much abandoned Cartoon Network. I later abandoned Nickelodeon when they started having more Live-Action Shows then Cartoons. Also I tried watching some of the shows by Seth McFarlene but I didn't find them to be entertaining at all (The only thing significant I liked was Stewie from Family Guy).
I pretty much listened to a recommendation from my brother about trying some of the Sci-Fi anime shows he had watched that I might like FLCL and Ghost in the shell: Stand Alone Complex. I found them to be entertaining and they actually had a story rather than random bullshit you find on the Cartoons now.
So basically The older Cartoons were awesome! But if you actually want to watch something decent don't watch any of the newer cartoons, try watching a bit of anime instead and see if you like it.