I use the pigeon peristiatic nipple in the avent bottles. Only coz i stocked up on avent bottles but DD refused to use them.

Avent bottles leaked all the time for me (coz i use a different teat probably) but I like how the lid is flat. The pigeon ones arent and can be rather annoying.

Avent has BPA (they are bringing a new range out that are not but dont know when), I thnk their plastic number is 7. Pigeon bottle number is 5.

best of luck and hope you find one that suits bub =)