The largest seller was Naya Rivera and Grant Gustin’s cover of Smooth Criminal, selling 108K all on it’s own.
In fact, it ranks as the 3rd highest debut for a Glee song so far in Season 3, behind We Are Young and Rumour Has It/Someone Like You.
two of the highest selling songs of the season heavily feature naya’s voice
Although in the full version of We Are Young (i.e. not the show one) Naya is also pretty dominant in it, so technically she could be in all three :D