The competition is heating up on Glee now that two singing groups, New Directions and the Troubletones, are at McKinley High. On the show's November 15 episode, rival teachers Mr. Schuester (Matthew Morrison) and Ms. Corcoran (Idina Menzel) decided to spark a friendly competition by having the crews go head to head for a mash-up challenge. Glee is no stranger to combining popular tunes into powerhouse numbers, and this time the show looked to songs from popular artists like Adele, Hall & Oates, Lady Gaga and Pat Benatar. We want to know: Which mash-up did you like best? Vote below!