I strongly recommend the Playtex Drop-ins. Due to concerns regarding BPA, I chose the Born Free bottles, but my daughter had a lot of gas when using them. We resolved her gas problems by adding the Playtex drop-in liners to the Born Free bottles; however, it's difficult to warm the milk in the Born Free bottles when they have the liners. My husband and I liked the performance of the Playtex drop-in liners in regards to the gas so much, we purchased the Playtex Drop-In bottles for daycare. My daughter didn't have any problems switching from the Born Free bottles to the Playtex bottles, and now I even use the bottles when we go out since they are hassle free and milk can be warmed by just placing them in water. I say save your money and go for the Playtex Drop-In system. Now I use the Born Free bottles to carry water when I need them, and, if you've seen how much they cost, it makes them very expensive water bottles.