Worst: Britney Spears

When pop princess Britney Spears first started dating an incredibly fertile and somewhat shady-seeming backup dancer named Kevin Federline, no one could have predicted that K-Fed would become the more promising parent of the two. But, over the years, Federline has proved to be the stable influence in the lives of their two sons, Jayden James and Sean Preston, while Britters has faced a distressing series of battles with the law, child services and reality. That said, it's been years since she was spotted driving with her son on her lap, and after her 2008 breakdown, Britney has seemingly pulled herself back together. In 2010 she was declared a 'fit mom' by California authorities.