Results always vary depending on the offer you are promoting. However, there are a few sites like Sotam, List Joe, TheLeadMagnet, Bweeble, ListBonus, Traffic Bonus, Herculist etc. that usually give good response. You always have to test your offer though, some offers may perform well in some sites and other offers may perform not so well in your favourite mailers but they could perform well in other mailers or elsewhere.