Plenty of shows fit into that category for me, mostly because either A. they jumped the shark as mentioned above (i.e Simpsons, Rugrats, Spongebob, FOp etc) or B. because i found them boring after a while.
Also the more data you gain as you grow up your favorite cartoons change obviously as you realise some cartoons are not as worthy as you once thought and vice versa.
The more obvious non shark jumping examples for me would be Tutenstein, which at first i liked but which got boring to me after a while, The Simpsons (earlier seasons) which after watching so many times got boring, Family Guy (though i don't dislike it, just find it duller than i used to, maybe because at the time i wasn't as used to the edgier humor in it)
Hmm they say i should do more paragraph breaks so i will. Hmm... Teamo Supremo... Being Ian... (though i'm more bored of it than disliking it) Angela Anaconda (though i'm more bored of it than disliking it) and some others... my memory fails me again