Can't remember the last time I saw a "new" episode of either show, actually. Family Guy makes me laugh more, but I still have a sense of loyalty to the Simpsons (somewhat diminished after the movie, though).
Truth, although I haven't seen the movie. The Simpsons were around when I was a lot younger though (they're probably going on 15 years or so aren't they?). You can't just pick one over the other if one was a childhood favorite.