Judging by #DancingABC instagram page and couples pics the most popular is Sasha from PLL (over 70.0000 likes&over 2000 comemnts) tagging behind her (with 50.000 likes&500 comments) is Nick then come all the rest with between 20-15.000 likes).
PLL fandome is HUGE all around the world that will take sasha far even if she can't dance but I think she at least has rythem since both her parents are dancers