Considering I forgot about it and got back into it, bringing back memories, first slot definitely goes to Franklin.
I'd definitely say second would have to go to a show like Ed Edd n Eddy since I used to watch way too much of it, I think...
And third would absolutely be a toss up since I watched way too many cartoons growing up. So I'd probably have to go with Death Note since it's the first anime I recognized as anime instead of just a cartoon back when I was in freshman year highschool.
Edit:
Someone mentioned Invader Zim and that would definitely be a contender because that show made me start to like weird and sometimes disturbing things. Here's looking at you, Dark Harvest. Also saw an Angry Beavers mention. Definitely a close 3rd since beavers are my favorite animal thanks to that show and Franklin.
I assume currently any AI they might be making would have some level of sanity to it and will give sane responses. So if enough people poison the data, the number of sane responses would probably go down if there's more LinkedIn Lunatic type responses in the training data than normal responses.