I had my first baby a few years ago and nursed her for about 6 months. After that and when we supplemented with a bottle we used Avent bottles. My baby was cranky and gassy and according to Avent's website, "A clinical trial demonstrated that at 2 weeks of age, babies fed using the AVENT Bottle, experienced less colic than babies fed using a conventional bottle". So I tried them among a few others for my babies first bottle.
This was great until I became aware of the concerns over BPA, a chemical that is part of the bottle. I did not become aware of this until my 2nd baby was born and thankfully I knew to seek out either glass bottles or BPA free plastic ones.
According to the Environment California Research and Policy Center, in 2007, "Popular Baby Bottles Sold in California Leach Bisphenol A at Harmful Levels." Among the brands listed are Avent, Dr. Brown's, Evenflo, Gerber and Playtex
Since this time, Avent appears to have come out with a BPA free bottle. I have not purchased any as I switched my second baby over to Born Free bottles, using the Avent nipples. While the Avent bottles worked better with the nipples I really don't' feel I should patronize a company who has been allowing harmful chemicals to leach into my babies milk for years. I only used the nipples because my baby had become accustomed to them and no other brands were agreeable to her.
If you are not a grudge holder like me, I'd say Avent bottles work very well for gassy and colicky babies. There are many brands to try and I'd say you need to find the one your baby seems to like the best and look out for BPA. If at all possible I believe using glass is much better than any plastic product. You just have to be careful with older babies to avoid dropping them.