According to the University of Glasgow, in a study that they conducted, dogs like reggae and soft rock over other genres of music.
A group of dogs were played a selection of different music types and, when music was played the dogs were more relaxed than when not. When reggae and soft rock was played the dogs had lower heart rates and stress levels.
The university decided that this suggested that dogs like reggae and soft rock music the best.
I can support this view as, when my dogs were younger, I would leave a radio on whenever they were left alone, the music would be classical rather than contemporary, and the dogs would always settle down and relax when it was played.