You've probably heard the György Ligeti "Lux Aeterna" before - it's one of the composer's three pieces to be featured in the film 2001: A Space Oddysey. Being Kubrick, however, he didn't bother to ask for permission from the composer, who was slightly annoyed at not being asked first and having his music jumbled up with Strauss and other composers, and very annoyed to discover that Kubrick had electronically processed one of the three recordings to alter its sound.
That Ligeti is part of his Requiem mass, and those are usually a good place to start for choral music. Mozart, Vivaldi and Fauré are all fantastic pieces of music... actually, any Requiem by a good composer is worth a listen - doing a Requiem mass was seen as the pinnacle of a choral composer's career.
That's part of the problem with choral music - because there's so many settings of the same text, the titles aren't that helpful: there's probably over a hundred settings of the Magnificat text, so you need to know the composers too (and some have done it more than once).
Suggestions:
Antonio Vivaldi - "Et Misericordia eius" from Magnificat (actually, the whole Magnificat is only 15 minutes). Also, his "Gloria" (a standalone piece) is good.
Richard Wagner - "Beglückt darf nun ..." (the Pilgrims' chorus) from Tannhäuser (the standalone arrangement, rather than the one from the opera; Wagner kind of buries this, the best tune of the whole opera, in the background in the original opera).
For more modern composers, try Arvo Pärt (Magnificat), Eric Whitacre (Lux Arumque), Ola Gjielo (Spheres, or Northern Lights)