I would have to agree with Adeels earlier post about Clickbank, in respect to returns they have a very liberal policy.
As far as affiliate marketing finding a product to promote is much easier on Clickbank than on PDC.
As far as finding affiliates to promote your product (if you are a newbie with out name recognition) you will get the same response from Clickbank or PDC.
The one affiliate network I don’t see mentioned here is Commission Junction…
What do you think of them as compared to Clickbank and PDC.