American Dad is what Family Guy used to be. It's too bad it doesn't do as well in the ratings as its parent show.
I don't watch it regularly anymore but I find this to be the easily superior show now. Subtle humor and fun characters with existent storylines. May not be "laugh out loud" like Family Guy but I enjoy this one much much more.
And if the show is still around in 6 years, people will be posting in the "Why American Dad isn't funny anymore" threads.
It's how these things generally work.