All In One are a popular choice for mums on the go. There's no folding or stuffing, its literally all done for you. They are generally pretty quick to put on and can be fastened using poppers or Velcro. There are some downsides though... having the absorbent insert permanently attached to the shell can mean that the drying times can be slightly longer than their All In Two sisters, and it can also mean that your stash could cost more as you wont be able to just change the inner each time and re use the shell. That being said; they do tend to hold their value and resale is generally pretty easy.