People who tried something and they like it wouldn't necesserely tell you becase they don't want to make competitors. People usually like to suggest good CPA networks but not quality traffic sources. Becase every new advertiser who joins affects CPC. If you pay 30 cents per click in your niche and other 100 people join, you'll pay 40 cents. Who wants that? On the other hand more advertisers means more traffic volume. So it depends. The best approach is to test different systems by yourself by little amounts.