When my grandmother died, the recessional hymn for her funeral was Salve Regina. My parochial vicar chanted it and it was beautiful.
I also love Regina Caeli. We used to sing it during Easter at another parish.
I also love to chant the Pater Noster along with the Holy Father whenever I catch the papal audiences and the papal Mass.
These are my other favorites:
Iesu Dulcis Memoria
Attende Domine
Te Deum
The Litany of the Saints
Veni Creator Spiritus
There is something deep and piercing about these chants. They penetrate at a deeper level than other music.