There are only 5 possible ad placements on Facebook!
We have two right column ad placements on desktop (homepage and non-homepage), two mobile options (mobile newsfeed and mobile apps), and desktop News Feed.
Some people have a blind predisposition to running News Feed ads because the CTR is higher. Others believe mobile is better, since the cost per click is often lower, especially when it comes to video views.
And then there are those who say right column (or called RHS for Right Hand Side) is best for direct marketing.