I used QuinStreet when I was a member of the marketing team of a company that was acquired. They were excellent at what they did. Their system was flexible, easy to use, and they built their own database and their own analytic system. They were very responsive to our technical questions. Nothing about the service. They didn't offer any training, and their support staff did not seem to be able to answer questions.
If you want to do some heavy customization, it would be nice to have more training