I can’t believe no one mentioned “Torah” by Shmuel Brazil, sung by R’ Abish! It’s about T’shuva and very soul-stirring.
Also, like oomis mentioned, there are so many gorgeous songs from t’fillos; my particular favorites are Avinu Av Harachamon (not Tatte) and R’tzeh.
Oh, but there are just sooo many BEAUTIFUL songs out there!
“There’s nothing like a niggun, it’s music for your soul!”
I once told R’ Abish (through my husband) “Thanks for giving me a daily mussar seder.” He responded that that’s exactly what a good song is: mussar!