Even though American Dad and Cleveland Show eventually departed from the Family Guy formula, I still can't bring myself to watch another episode. Even though they're funny and entertaining I just can't enjoy them, probably because I'm a biased jackass who doesn't want to waste his time. I like what I like and don't like what I don't like.
I guess because all of Seth McFarlane's shows feel so formulaic and passionless they don't register as anything but a "me-too!" attempt at something successful. The Simpsons had a passion for its world and characters from the get-go, and Futurama proved itself to be special and worthwhile instantaneously (being such a radical departure from anything on primetime at that point, it had to put up or shut up). Meanwhile, everything McFarlane does is a jack-in-the-box that makes a fart sound when it pops open. Maybe after 30 or so times it tells and actual joke, but I don't feel like sitting through another couple dozen farts in the face to hear another one.
Delivery, then, is the dilemma. Case in point: how the Simpsons and Family Guy handled the subject of gay marriage. In the Family Guy episode, Brian's incredibly gay fitness instructor cousin (brother?) wants to get married to his incredibly gay latin boyfriend, whose name I don't remember. When the mayor bans gay marriage, Brian takes the mayor hostage and threatens to shoot him if he doesn't repeal the law.
In the Simpsons, the town of Springfield legalizes gay marriage to increase tourism and get some much needed cash for the town. Homer then becomes a minister and starts marrying anybody to anything because of the money in it. When Marge's sister Patty comes out of the closet, Marge is a little unsure of how to respond. Then Marge finds out Patty's fiancee is secretly a man, and puts a stop to the wedding to spare her sister's feelings.
In Family Guy, the humor comes from the mayor barfing up board games while captive, and the subject of gay marriage is little more than a plot device to show how much the TV show is in support of gay marriage. In The Simpsons, many aspects of homosexuality, religious beliefs and human motivation are explored and are in conflict with one another. It's a topic that doesn't affect one person, but a whole town, in more ways than "this book says its wrong" or "I think it's right because I think you're wrong". In the Simpsons, people are forced to face painful changes and grow as individuals, while in Family Guy the status quo is simply moved to where a few people believe it should be.
I would guess from the article that the Cleveland Show leans more towards the character-driven and character-affecting style of the Simpsons, and I might be wrong in thinking that it's simply a delivery vehicle for one person's morality. But that's really the vibe I get from every episode of every McFarlane series I've seen.