Which option is best for webcam affiliates of these three choices...

[tphelan]

I haven't been an affiliate for webcam sites before and am hoping someone here has an opinion on this question:

Of the three options some webcam affiliate programs offer which one have you found out to be the best choice:

1. One time payment for each signup. Lets say $100 per paying member.
2. Lifetime percentage of purchases per customer. Lets say it's 20%.
3. A small one time payment for free members. Lets say $1 per free member.