I think it's clear by now that the Gondorians are all into Disco music, and this is why the title 'the Disco king' was borne by every Steward's first born.
The hobbits are all into traditional stuff, like it's been said by almost everyone, they like easy-going tunes with nonsensical lyrics.
The Rohirrim i see them listening to goth or metal. Yes, they are that cool.
The Ringwraiths and Sauron listen to girl and boy bands(brilliant idea whoever thought of this

).
The Elves are all for classical music, especially Mozart, Rachmaninov...the 'lower' Elves go for musicals and operettas.