This summer is youtube popular cover hit song “Problem” by singer Ariane Grande. Here are best covers so far from acoustic versions to hardcore versions and collage of all.
Sometimes cover is better from original song. One of them is surely “I Follow Rivers” Swedish singer Lykke Li and worldly famous cover from Danish band Triggerfingers. In Slovenia they made cover Modrijani, Tabu, Alya and many more.

Youtube artists made many covers of the song “Problem”:
- Madilyn Bailey (Acoustic Version) http://youtu.be/CNdTk8Y9iUs
- Pentatonix (acapella) http://youtu.be/4Z9b2HiW_L8
- MAX & Kurt Schneider http://youtu.be/SiQrPnBcgdo
- Rixton http://youtu.be/MkmTjZdvgBQ
- Maria Zouroudis http://youtu.be/y4Ex4cASODs
- Pellek (metal cover) http://youtu.be/y4uwvNai0iM
- Alexi Blue (acoustic) http://youtu.be/Mtsdv6CXel8
- The Janes (acoustic) http://youtu.be/QGIILbm57g0
- Bart Baker (parody) http://youtu.be/4_qKaiGqALo
 
- PopToonsTV (cartoon parody) http://youtu.be/1ROFzco2rz4
- Ali Brustofski http://youtu.be/lo2HKH4ZPO8
- Airspoken (post-hardcore) http://youtu.be/fYf9v7yvZXE
- Hannah Trigwell http://youtu.be/5vA4k-voYjg
- Mahogany Lox & Brandon Skeie http://youtu.be/uouJN13sJMM
- Laura M Buitrago (spanish) http://youtu.be/OKLJWfHkofA
- collage by Seventeen http://youtu.be/JPvREHkjRjI
My best four covers are: acapella Pentatonix,  blue from Max & Kurt Schneider, acoustic Madilyn Bailey and band Rixton.