>>>it leaves it open to one's judgement
could it really be otherwise? might as well ask for the definitive answer to the question, "who was the most influential rock band of the 60s?"
tell the individuals' theoretically complaining that you've chosen the "wrong" genre for an artist to "get their own boat"
You could have one genre (like "music") for all your songs, and use the custom boxes to sort the music by some less subjective criteria, such as "mood," or songs mostly preferred by males/females"
Lastly, if one were to object to a genre that I had chosen for an artist, I would invite them to write an essay explaining how their position was superior to my own, and tell them that once submitted, I'd review it and consider whether a change was warranted before deciding against their recommendation.