So I've gotta say its made great strides recently, but when I hear pop music for a long enough time it inevitably makes me angry with the music industry and its production. There is good, and bad pop music, and if its on my own playlist, or one of those rare stations that just plays the good stuff regardless of what time, or trend is going on then I'd say either works. But in general, the producers in the pop industry and their reputation make it harder for me to focus on studying. A lot of stuff is actually made by the same small groups of people, and just sold through the band, and it bothers me.
Classical music like Fur Elise by Beethoven can make you feel calm and peaceful. Classical music can make you concentrate on study. Research shows that classical music is the easiest to enjoy. Classical music don't just can concentrate on study, it can also use for meditation too. So classical music is the BEST type of music to use for study.