I was very pleased to discover chorusonline recently. The repertoire selection is really good and the packages of arrangements, sheet music and mp3s is just what I need for my choir.
Strengths
Repertoire choice, packages with backing tracks and prices based on choir size.
Improvements or suggestions
The SSA arrangements that's I've purchased are a little tricky and effectively split into 5/6 parts at times. The choir are capable of it but it takes time to learn.
Reply ChorusOnline.com:
We try to indicate the level ( I-V) based on our experience.
It's good for a choir that sometimes the level is up to IV or even V ... they really have to study then.
ChorusOnline