Retin A or Benzac (Obagi or Pro Activ)???

I am a 26 year old female that has been dealing with acne since I was 12. I am currently using the Obagi Nu Derm program, while I find my skin feels nice and looks healthy, I still deal with spots and enlarged pores. I have been looking into Pro Activ and found their main ingredient was Benzoyl Peroxzide. I have used this ingredient before, and in my eyes they controlled to a certain level, and with both still got pimples. My skin is completely hormone balanced, and due to allergies I can't not take any prescribed medicines for my hormones. Out of all of this, which way is the best way to go and what are the side effects of using either product for such long periods of time????