Steve C. said: "It's pretty hard to argue with "Show Business" as the best. I had never come across the film of "Call Me Madam" until finding it on FXM Retro. What a show; Ethel Merman is a real tour de force! It ran for about 700 performances in the 50's. (with the great Tommy Rall too) Great Irving Berlin bouncy cute score, including this gem, "You're Just In Love" with Donald O'Connor.
"You're Just in Love" is probably the greatest counterpoint duet written for the theater. Some might choose "Lida Rose" from The Music Man. I wonder why more composers didn't write any. They are fun.
Here is MGM's anthem to show business, written by Schwartz and Dietz for the 1953 film The Band Wagon. In November, 2015, City Center produced a Kathleen Marshall musical version. Some clever lyrics, here performed by Judy Garland (short):
It might be a fight like you see on the screen
A swain getting slain for the love of a queen
Some great Shakespearean scene
Where a ghost and a prince meet, and everyone ends in mincemeat.
https://www.youtube.com/watch?v=ibSwgWj6JiY