I think more specifically, the "Freed Unit" at M-G-M churned out the greatest musicals. Arthur Freed was a genius. Ofcourse, others like Joe Pasternak made great musicals too, but I think it was Arthur Freed who made the Golden Age of Hollywood musicals.
Some of my favorite MGM musicals - The Wizard of Oz (1939), Meet Me in St.Louis (1944) and Singin' in the Rain (1952).
MGM made some fabulous musicals, a little sad that most any filmusical prior to WW2 seems to be neglected re MGM, they also made the Great Ziegfeld, eyepoping numbers if you've never seen it, The Broadway Melody of 1936 two huge production numbers in this one, Rosalie, Eleanor Powell need I say more, Mgm were experimenting with stereo recording from 1936 onwards, some of these recordings are available on CD I'm thinking of Born To Dance, Artie Shaw Orch was recorded in stereo in 1938 by MGM for a musical I can't recall right now plus other big bands through the war years who appeared in various musicals, other studios also experimented with stereo 20th Century Fox recorded glenn Miller in Sun Valley Serenade & Orchestra Wives in stereo, also available on CD some of the Betty Grable musicals were recorded in stereo, this is proper 2 channel stereo and if you haven't heard them you will get an extremely pleasant surprise much better than the old mixed down to mono soundtracks we've heard for years, the reason the studios mixed their soundtracks to mono for commercial release was because sound had only become a reality a few years before the mid 30's and movie theatre owners had spent a fortune converting to sound and were not about to pay out another huge sum for their theatres to be wired for stereo, then WW2 happened which put commercial devolpment back, hence the mix down to mono, stereo wasn't a commercial proposition untill the early 50's when television started to take it's toll audience numbers, in recent years the films I've mentioned have been issued on DVD with the original stereo soundtracks It's like watching a different movie.