My son used only Avent bottles. They are BPA free and come in various sizes. The nipples are made of silicone, which is very safe for the baby, and they come in different flow rates. The bottles are durable, I've boiled them many times for the first 2 months and these bottles lasted until he was weened off the bottle.

One of the nice features of the Avent bottle system is that you can easily by accessories to convert the bottles to sippy cups, which also comes in different flow rate. You can also buy handle attachment for their little hands to hold onto the larger bottles. So this bottle truly grows with your baby and you save a lot of money.

However, the reason I am giving this a 3-star rating is that these bottles LEAK!! They Leak Leak Leak!! You have to align the nipples to the white cap a certain way or it'll leak while the baby drinks the milk. It also leaks when you switch the nipples to the sippy cup spout. It's very frustrating.

One last thing about the sippy spout: it's not a good starter spout because the baby has to suck pretty hard to get the liquid out. My son couldn't go straight from nipples to sippy spout of this design. I actually bought him a silicone sippy cup of another brand, got him used to the idea of sucking on something other than a nipple, then switched him back to the Avent bottles with the Avent sippy spout.

I wouldn't buy these bottles again because having to deal with the leakage is not worth the trouble. I'd rather pay a little more and not having to deal with drippy bottles and sippy cups.