There are so many. I was raised on Rogers and Hammerstein so I've some favorites there. "Oklahoma" is arguably my favorite musical, but then I think, no, Grease, no Rocky Horror....Little Shop of Horrors.
Songs..
On the Street Where You Live - My Fair Lady
Shall we Dance - The King and I
I Had a Dream - Les Mis
You're the One that I want - Grease
Time Warp - Rocky Horror
Can you Feel the Love Tonight - The Lion King
Oklahoma opening number - Oklahoma
The Trolly Song - Meet Me in St. Louis
New York, New York - On the Town
Heaven on Their Mind - Jesus Christ Super Star The Movie (sang by Carl Anderson, he nailed it! (pun intended :-)
so many more, I love musicals