What should I use to exfoliate my skin?

I have heard and read different things about exfoliation. Some say that AHA for dry skin is best and BHA is best for combination to oily skin. I also read that both AHA and BHA (alpha Hydroxy acids) give better results than using facial scrubs because they remove dead cells  through chemical processes and penetrate the superficial layers of the skin. Cosmetic scrubs work only on the very outermost skin layers and can actually cause skin damage and tears in the skin if they are too coarse or uneaven in texture.

That makes sense to me but then I heard that peptides are the new thing?  What are peptides and how do they work to exfoliate your skin? What is the difference if any between peptides and copper peptides?