PPC or PPI

United States
February 5, 2007 9:36pm CST
I am in need of advice from people who use the paid per click and paid per impressions services that various companies offer such as google, adbrite, clicksor, ect. Keep in mind that paid per click usually pays a lot more than paid per impression. Which would you pick? And if you already use a service, please share which one.
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