Like SpeckledHen was saying FB and BYC are like apples and oranges.
Like any other webs, you just practice what you preach and "weed" out the bad ones from the good ones and after all you ARE in control of what you do on FB and whom you want on FB. You can moderate your own FB page.
There are pros and cons on both of them but I am not going to say too much more because I have been on BYC such a long time, fads come and go, people come and go, and I do notice we are more opinionated than ever before in the Random Ramblings sections.
With the religion and poltics debates, some of us like to banter back and forth, expressing opinions and whats nots, it would be best to go over on FB. Or anyone that wants to play with fire.