Family Guy is very formulaic in its later seasons, very hit-or-miss all the way through.
I have ALWAYS found it funnier than The Simpsons, and definitely better than both of its spin-offs. There are some of the most classic jokes in animated comedy to be found in this series, but also a lot of really stupid or boring episodes or premises.
They attack practically everything in life, so it's not for the easily offended. The show absolutely absolutely has a hard leftist bent, though. While they bash the left every now and then, 99% of their political humor is bashing the right, and it's noticeably lop-sided.
Comparing it to something like South Park, though? I could never miss an episode of South Park. I went about three years without watching Family Guy and did not miss it, but when it occurred to me to catch back up, I haven't regretted it. It's not as funny or edgy as it used to be, but at least Seth MacFarlane isn't singing in EVERY DAMNED EPISODE anymore.
South Park, Beavis and Butthead, Family Guy. That's the top three, in that order, when it comes to animated adult comedy shows.
