best plugin for managing discounts.

Here is the problem I am trying to solve.

1. I want people to register to create a mail list.

2. The product I supply is a website security audit. and I want to issue 2 kinds of discounts ( I may run these on a domain and sub-domain for the affiliate if I can somehow tie them together for admin):

2.a. an affiliate which is tied to the affiliate, (affiliate 1 20%, affiliate 2 25%, affiliate 3 25%) to track the affiliates referrals.

2.b. a registered user exclusive discount so when “Able Baker” registers, part of the registration process is an email confirmation of his email, and he gets a discount code “Able B. 20%” that only works for him and his email. when “Bravo Charley” registers he gets his own “Bravo C. 20%” code but he can’t use “Able B. 20%”. that won’t work. but either can use the ‘affiliate 1 20%”

the question is: what is the best plugin to deal with this?