Very cool list. And very correct to establish criteria first. E.g. although I don't dislike ALW, I think of his work, like Les Mis as opera rather than musical, given the latter is usually more spoken dialogue than sung.

Much as I love West Side Story, I find the Broadway version unlistenable because they included much of the dialogue in "Tonight" & Maria's faux-Spanish accent is painful on the ear. Natalie Wood's is only slightly less awful, but perhaps there is less of it in the track.

Mary Poppins would be the greatest of all musicals if only for the annoying mixed animation scenes. I get Walt Disney believed he had to use animation as it was the studio's trademark. Travers was right to call him on it. People also cite Dick Van Dyke's faux Cockney accent as an irritant, which it certainly was. I think Van Dyke is too acute a student of method to have created it intentionally. I can only guess director Stevenson thought it would add to the film's charm.

And ... the Sound of Music. Hate the film, love the music. Much of Rogers & Hammerstein's best. It's been criticized as being putatively anti-Nazi while also being exactly the kind of film the Nazis loved. That's not a valid criticism—even the Nazis are allowed to appreciate a fine film. For me, it just grates.

And, speaking of Rogers & Hammerstein, no Oklahoma! or South Pacific?

Much as I appreciate your shoehorning La La Land into the list—it glorifies my hometown & is a fine musical besides—I'd had put one of the above in its place.