With that number of people I would try to put the choir in an arch and then place one mic in the center of the group. Audix makes a very low profile mic system that would probably work well for you. I am not a huge fan of hanging mics just because it reduces the flexibility of your stage layout and of what you can use the mic for. That said, if your stage never changes and the mic does not ever need to be used elsewhere, a good hanging mic can be the right choice.
Peace (Phil 4:7)