As far as smart comedy, it 's Family Guy for sure. Now, Simpsons USED to be witty and funny, but ever since Conan O'Brian left as a writer, it went downhill. Now it's simply stupid, off-the-wall antics that try and force laughs out.
So I would have to say, it would be a close call if you were comparing Family Guy to...let's say...the Simpsons 4th season, but if you compare it to the Simpsons now, it's not even close. Only South Park and Futurama can give Family Guy competition