It all depends on the purpose of the voice samples. If they are fillers to link a story, then use movies, TV shows and commercials. If you need them for harmony, seek motown, R&B, or some good old lounge jazz music. Don't be afraid to try $5 vinyl singles and CD's. There is a lot of gold in unexpected places. And, Don't be embarrased to go to a store and purchase a Dianna Ross or Ella Fitzgerald album