I voted "CD recording" (the TAC in my case), but on second thought, I feel like I should have voted for the 2012 movie.
The first time I heard of Les Mis was when my high school glee club did a medley from the musical. I think it consisted of At the End of the Day, I Dreamed a Dream, Castle On a Cloud, Do You Hear the People Sing, On My Own, Bring Him Home, and the Epilogue. I fell in love with the songs and bought the TAC CD. Shortly after that, I saw a high school production of the musical (the only stage production I've seen to date).
Then my interest faded for, like, 10 years.
I still loved the music, but I don't think I fully understood and appreciated the story until I saw the 2012 movie. After seeing the movie, I read the Brick, and now Les Mis owns my soul.