If you listen/have listened to musicals before, what's your favorite musical and favorite songs within each musical?

I'm going to be that guy and tell you that the best musical of all times, which can never be beat, is The Sound of Music. Anyone who disagrees is wrong, and anyone who thinks that West Side Story is better is double wrong. :P

I could go on and on about the music, but I'll keep it short. One of the reasons why I love it so much is that it took the musical idea of theme and turned it to 11; for almost every major song, there is a reprisal that comes up and builds up on the emotional scale. Lets take a look at one particular example; Do-Rei-Mi. This is one of the longest songs in the soundtrack, and that's because it's actually three songs in one. The first one is a simple primer, getting the audience ready for the song that's coming up. The second part is when all the children start singing along. And then the third part is basically a reprisal of the second part, where the basic melodies are given crazy variations and new harmonies are introduced to really get you excited. Put together, this song delivers a sense of exhilaration and joie de vivre that you can't easily match otherwise. And the way that these songs are "doubled down" with reprisals is used throughout the musical to great effect.

Beyond everything, Climb Every Mountain is the most inspiring song you will ever hear. I would recommend getting a copy of the restored edition of the original cast recording because the performance really makes it; the tempo is entirely controlled by the voice of the singer, who introduces natural variations in it that really drive those emotions home.

While the film version of the musical fumbles Climb Every Mountain (to the point that I honestly think it ruins the ending), it's worth watching just for the cinematography. It's just incredibly beautiful in just about every frame. The film replaces the love song "An Ordinary Couple" with "Something Good", and honestly, I think it's a much better song; combined with the way it is shot, it does a much better job at selling the relationship than any other musical I've ever seen (and given that practically every musical has at least one love song in it, that's a high compliment)!

The only other musical that comes anywhere close to the achievements of The Sound of Music is Les Miserables. And to be honest, the only real reason why I don't rate Les Miserables is that I feel that the way The Sound of Music uses reprisals is a better innovation to the genre than the traditional use of themes that Les Miserables uses. Though to be fair, I love them both just about the same, and I have probably shed more tears over Les Miserables than The Sound of Music.

Musicals have a really broad range of styles, and have been around for a really long time. Once or twice a generation a new composer comes in and flips the previous stylings on their head. The "subgenres" of musicals are very different from each other, and people who really like musicals of a certain style don't necessarily like the others from different styles. If you're just getting into it I recommend listening to musicals from different composers and eras to get a feel for what you like.

Here are notable ones, in chronological order, listed along with others like them. I may be missing things. :)

• Oklahoma! (1943) is one of the more famous examples of the typical "classic" Broadway musicals, and at its time was one of the first musicals where the songs were integrated with the script to tell a coherent story. It's written by two people named Rodgers and Hammerstein, like most of the other "classic" musicals from this era. Musicals in this time period roughly follow the Hayes Code similar to films of the era, and have very strong 40s-50s sensibilities. Other notable examples of musicals like this include The Sound of Music (1959), The King and I (1944), and Cinderella (1957).
• Hair (1967) was one of the first major musicals to have an edgy tone, deal with serious themes, and use rock as its main genre influence. Other notable edgy rock musicals include Rent (1996), dealing with the HIV/AIDs crisis, Spring Awakening (2006) dealing with multiple teen issues, and Next to Normal (2008), dealing with mental health issues.
• Stephen Sondheim is a composer with a very distinct style who has single-handedly produced dozens of famous musicals over the past few decades. I'm breaking my own rule and listing him instead of any one of his pieces because it's impossible to pick out a single one that defines his style. His musicals all have very emotive music that isn't "catchy" but is extremely demonstrative of the character's emotions, but are also different from each other in tone and content. It's like a cross between traditional Broadway and jazz, I'm sure somebody smarter than me has a better way of describing it. Company (1970) is a drama about intimacy, Sweeney Todd (1979) is a dark comedy about a serial killer, Into the Woods (1987) is a fractured fairytale based on the Brothers Grimm, and West Side Story (1957) is a retelling of Romeo and Juliet set in the 50s in NYC. (Edit: Sondheim only wrote the lyrics, not the music, for West Side, and I originally confused Company with another musical.)
• The Phantom of the Opera (1986) is a dark drama that has a blend of semi-pop, semi-traditional Broadway music. It's famous for being one of the longest running musicals of all time. I'd consider it the straightforward modern evolution of the classic R&H musicals from the 40s-50s. Wicked (2003), a retelling of the Wizard of Oz, Les Misérables (1980), a drama about the French Revolution, and The Lion King (1994) are other famous musicals that fall into a similar category.
• Mamma Mia! (1999) is one of the more popular jukebox musicals, or a musical where the story has been written around a pre-existing set of popular songs. Mamma Mia! was based on ABBA's music. Other examples of this include Moulin Rogue! (2001) which used songs from various pop artists, Jagged Little Pill (2018) which used songs from Alannis Morissette, and Jersey Boys (2005) which used songs from The Four Seasons.
• Legally Blonde (2007) is a comedy musical that adapted an already well known non-musical film. It has a mix of pop and classic Broadway sounds. Other things like this include Mean Girls (2017), Beetlejuice (2018), and SpongeBob (2016).
• Hamilton (2015) was the first major popular musical to use rap as its main genre. It's lyrically and musically brilliant, there is nothing else like it.
• Hadestown (2019) is the first major popular musical I'm aware of that uses folk as its main genre influence.

I did check out the song you linked but couldn't really place it confidently among the stuff here. It sounded a little similar to Wicked. Wicked also has a fantastical setting and touches on some similar themes to Undertale the game, so you may have some luck starting with that one.

Double edit: after all that I didn't actually say what my favorites are. Hamilton (songs: My Shot, Satisfied) and Into the Woods (songs: Last Midnight, Giants in the Sky).

Easy. Sweeney Todd: The Demon Barber of Fleet Street. Specifically the 1979 version by Sondheim. While I have a fondness for "A Little Priest" due to its elaborate wordplay about how different professions taste when cooked into pies, "My Friends" is the one that always sends shivers down my spine. The relief and joy in Sweeney's voice as he gets his razors back combined with the resolution of the piece is just so good.

Generally speaking, I'm biased towards shows that I worked on as an amateur theater tech.

Number 1 is Les Miserables by a longshot - it's the show I've seen live the most often and will continue to go see new stagings of whenever I have the chance. My high-school tech director actually met Colm Wilkinson after a showing of the original Broadway performance, and she and her friends ended up hanging out at a bar with him and some other castmembers that night.

Number 2 is Into the Woods - it was our senior-year musical and was the most complex show I stage-managed. While Sondheim may occasionally be hard to sing along to, Into the Woods is still a show that's basically perpetually stuck in my head.

Number 3, I'll go with a less-popular show in Thoroughly Modern Millie - it was the first show that I did my own lighting design for (which became my preferred area of focus (ha, focus)). We also had an extraordinarily-talented cast that year, so we put on quite the performance.

I usually listen to metal but have a soft spot for Glee...a fact that's always fun to mention on metal forums. Anyways, Glee might not be a musical per see and is disliked by a lot of different people including traditional musical fans and for the exact same reasons I love it. I have a thing for super clean vocals, harmonies and I love their renditions of popular songs with crisp production. On the other hand I don't like traditional musicals at all. They're silly, theatrical and the music is just not appealing to me for the most part. This could also easily be said about Glee so I guess it's just preference.

No love for Avenue Q here? I don't think I've ever laughed harder than the first time I saw it! How can you go wrong with songs like "The internet is for porn"?

Chicago – We Both Reached For The Gun (2002)

Music by John Kander (1975)
Lyrics by Fred Ebb (1975)
Performed by Richard Gere, Renée Zellweger, Christine Baranski, Cleve Asbury, Rick Negron, and Shaun Amyot