Most of the album links are for Apple Music, but you should be able to find the albums on other sources as well (Spotify, etc.)
Some of Mr. Riggs' favorite albums
Robert Shaw Festival Singers: Amazing Grace - American Hymns and Spirituals
The Singers - Minnesota Choral Artists: At the River
The Singers - Minnesota Choral Artists: Lauridsen: Mid-Winter Songs
Conspirare: A Company of Voices
Conspirare: Sing Freedom! African American Spirituals
Voces8: Enchanted Isle
Voces8: After Silence
The King's Singers: Madrigal History Tour
The King's Singers: Annie Laurie - Folk Songs of the British Isles
The Men of the Robert Shaw Chorale: Sea Shanties
Chanticleer: Wondrous Love - A World Folksong Collection
The Dale Warland Singers: Lux Aurumque
The Tudor Choir: Gentle Words - Shaker Songs
Musica Intima: Clear
Anúna: The Best of Anúna
BYU Singers: Whitacre - Choral Works, Vol. 1
PLU Choir of the West: There Will Come Soft Rains - Choral Works of Eriks Esenvalds
The Seattle Girls' Choir: Jackson Berkey Meets the Seattle Girls' Choir
The Singers - Minnesota Choral Artists: At the River
The Singers - Minnesota Choral Artists: Lauridsen: Mid-Winter Songs
Conspirare: A Company of Voices
Conspirare: Sing Freedom! African American Spirituals
Voces8: Enchanted Isle
Voces8: After Silence
The King's Singers: Madrigal History Tour
The King's Singers: Annie Laurie - Folk Songs of the British Isles
The Men of the Robert Shaw Chorale: Sea Shanties
Chanticleer: Wondrous Love - A World Folksong Collection
The Dale Warland Singers: Lux Aurumque
The Tudor Choir: Gentle Words - Shaker Songs
Musica Intima: Clear
Anúna: The Best of Anúna
BYU Singers: Whitacre - Choral Works, Vol. 1
PLU Choir of the West: There Will Come Soft Rains - Choral Works of Eriks Esenvalds
The Seattle Girls' Choir: Jackson Berkey Meets the Seattle Girls' Choir
Extended Works
Ein Deutsches Requiem - Johannes Brahms
Carmina Burana - Carl Orff
Requiem - W.A. Mozart
Gloria - John Rutter
Messiah - G.F. Handel
Lux Aeterna - Morten Lauridsen
Requiem - Gabriel Fauré
Requiem - Maurice Duruflé
Gloria - Antonio Vivaldi & Magnificat - J.S. Bach
Some original extended works:
Spirit Song - Kenneth Riggs
Missa Campana - Kenneth Riggs
Stabat Mater - Kenneth Riggs
Starlight Songs - Kenneth Riggs
Carmina Burana - Carl Orff
Requiem - W.A. Mozart
Gloria - John Rutter
Messiah - G.F. Handel
Lux Aeterna - Morten Lauridsen
Requiem - Gabriel Fauré
Requiem - Maurice Duruflé
Gloria - Antonio Vivaldi & Magnificat - J.S. Bach
Some original extended works:
Spirit Song - Kenneth Riggs
Missa Campana - Kenneth Riggs
Stabat Mater - Kenneth Riggs
Starlight Songs - Kenneth Riggs