Actually the one thing that drew me to Family Guy over the Simpsons when it was on the air was the fact that Family Guy had the heart that the Simpsons has lacked over the past several years. When I watch older episodes of the Simpsons, I can see the comparison, but comparing FG to the recent episodes doesn't do FG justice.
There have been many direct copies (or maybe cases of writers overhearing other writers). The "Jebus" thing was done on FG first, when it was a typo in the bible. About six months or more later, on the Simpsons missionary episode, Homer uses that to prove he's not too keen on his religion (or just doesn't pay attention). There have been others, but I'd have to really refresh my memory to recall them.