Bamboo, Cotton, or Hemp?

SharmenLisa

We are looking to do prefolds/flats and covers during the day and maybe fitteds at night. What is the best as far as absorbency goes. 

Also, I know that a single prefold or flat won't work forever and I was thinking I might add some inserts eventually to increase absorbency without increasing bulk. What should I be looking for? Bamboo, Hemp, a bamboo and microfiber blend?