Both The Simpsons and Family Guy blow chunks right now. The writing on the Simpsons has been horrible since 1999-2000 season. And Family Guy fell apart about 2007-2008 season. In both shows All the characters have devolved into pale caricatures of themselves, supporting characters have become nonexistent, or insignificant and storylines literally repeat themselves.
The producers of the Simpsons are just phoning in it until the show is no longer profitable for Fox (means a 0.5 rating and impossible to sell to advertisers,) and they'll probably do an entire episode around cardboard cutouts with cell phones taped to them just for laughs if they could get away with it. Sadly, this idea would actually be funnier than anything the Simpsons writers have done over the past ten years.
Family Guy fell apart when it became a springboard for MacFarlane's liberal agenda with Brian becoming Macfarlane's mouthpeice. I have truly hated this show over the past two years; If I want to hear political and social commentary in my entertainment I'll watch the original Twilight Zone. The late Rod Serling owns Macfarlane infinity times over and serves him for breakfast lunch and dinner.
If Fox had some Juevos, like they did in the early 90's they'd take a risk, cancel both shows and rebuild their Sunday night.