What music in Warcraft, when hearing it outside of the game (youtube, twitch, social media, etc.), brings the flood of nostalgic memories. Memories that entice you to return and keep playing like a siren song luring sailors to their doom upon the rocks. Music so strong that just by hearing it creates the vivid images in your mind.
Even though I mostly played Horde, my first character was Alliance. So to me the Stormwind theme will be stuck in my head forever. A close second would be the Ashenvale theme. I am sure there are Horde themes, like the Barrens, that are as strong.
What are yours? And they don't have to be from Vanilla.
Stormwind
Ashenvale