These are some of the pieces by Forum composers that I have pulled over the years and have found to be fairly accessible and flexible for amateur choirs. We have used most of them and found them effective.

I just thought it could be fun to repost them here together.

I have about 12-16 voices at a time in the choir, am am short on men's voices. The split is usually 4-5 men out of those numbers. All voices are amateur, with occasional use of a women's section leader. Everyone learns by ear; there are no strong sight readers.

Patricia Warren/Kathleen Pluth
Jesus, Walking to His City

ServiamScores
Improperium Expectavit/ My Heart Expected https://www.youtube.com/watch?v=AVWQj2u5FPo
Take Up Thy Cross https://youtu.be/JUSsPlphtp4
Ecce Virgo Concipiet https://youtu.be/ZOkmutvcOJ4

Richard Rice
Easter Alleluia

Drake
Oculus Non Vidit
Jesu Dulcis Memoria

Giffen
Gustate et Videte

Christopher Garton-Zavesky
Jesu Dulcis Memoria

Heath Morber
Gustate et Videte

Jeffrey Quick
Ave Maria

Liam McDonough
Humbly I Adore Thee
Ave Verum Corpus
Verily, Verily
O Sacrum Convivium
Veni Creator
Attende Domine