What holds more?

I would say the pochette, if you mean the full size one - as in the Pochette Accessoires NM. The Cosmetic PM is cute but I find that even the GM size, which I have, doesn't hold as much as the pochettes can, due to the shape.
 
I have both, and if you are referring to the pochette nm, then it holds more than the cosmetic pouch pm. If you are debating between the two, I would only caution you to think about what you will be carrying, as only the cosmetic pouch has the wipeable lining.