I use Tommee Tippee and formula is Enfamil.
I have gone through Avent bottles, Medela bottles, and Dr. Brown's glass bottles. I loved Dr. Brown's but it was a hassle for me to keep cleaning each parts. I just am not a patient person. Finally, I opened Tommee Tippee bottles I received as baby shower gift. I like it and she likes it too.
We started out with Enfamil. Then I made the mistake of switching brands - I switched to Similac. Big mistake. She started to have major gas problems from that and made her poop turn green and smellier. So then, I switched back to Enfamil and she was happy again. The reason for the switch was because I had LOADS of Similac coupons that I didn't want to waste. Plus, Similac is dollars cheaper than Enfamil. Anyway, I didn't know that changing brands can cause problems for lo's tummy. If I had known, I wouldn't have done that.