Affiliate Marketing Secrets

I want to engage several affiliate programs online at the rate of one per week and I was thinking which of these would be “cheaper and effective with regards to Organic Search engine optimization ONLY”
www.xxxxx.com for each affiliate program (seperate domain for each affiliate program)
or
www.xxxxx.com/affiliate1 (and so on for affiliate 2…)
or
www.affiliate1.xxxxx.com (one domain for all affiliate but they will sit on different subdomains)
Thanks a lot.

I want to engage several affiliate programs online at the rate of one per week and I was thinking which of these would be “cheaper and effective with regards to Organic Search engine optimization ONLY”
www.xxxxx.com for each affiliate program (seperate domain for each affiliate program)
or
www.xxxxx.com/affiliate1 (and so on for affiliate 2…)
or
www.affiliate1.xxxxx.com (one domain for all affiliate but they will sit on different subdomains)
Thanks a lot.