Violin - Lindsey Stirling is the coolest violinist ever! She plays beautiful arrangements of pop songs, video game music, and more! Personal recommendation - Zelda Medley
Viola - Jeremy Green is basically the viola version of Lindsey Sterling! He does more pop music than video game music. Personal recommendation - anything!
Cello - 2CELLOS are the most iconic string duo in the history of orchestra! Name a more iconic duo - I'll wait. Personal recommendation - Thunderstruck (wait for it though!)
Bass - Francesco Tesei is a bassist and guitarist that makes some pretty cool videos. Personal recommendation - Bohemian Rhapsody