Mulgore, Elwynn, and Dun Morogh are my favorite by far.
Notable mentions: Teldrassil and Ashenvale.
I've played Barrens music whenever I had the urge to play, but that's kind of a cliché, so here's this instead
In Discord, we have a music bot channel to start Fredboat playback, and in the channel description, there is this one music music link (https://bit.ly/2AdJXHU) to rapidly search for the best filtered search query to playback Wow Ambiance.
Pretty much, the best zone sounds are:
- Elwynn Forest
- Howling Fjord
- Tirisfal Glades