There are so many brands, and even though we are happy with what we are using, I wished someone would have told us the pros and cons. I can't speak for all of them, but I will give my opinion about the ones we have tried.
NUK, their strong point is the teat. It is more flat than round (like all the others). When Leily was in her premature stage she wasn't able to put the normal teats into her little mouth. NUKs teats were perfect and we used them for the first two months. If Dr Browns didn't exist, I would probably go for NUK.
AVENT, they are the "simplest" bottles you can get. I call them the "standard" bottles. If you don't want anything fancy but still use a known and recognized brand, I recommend AVENT.
Dr. Browns, their strong point is their air flow system, which in my personal opinion makes a huge difference when it comes to winding your baby. Basically the bottle comes with this tube which lets the air (all those bubble that usually gather on the teat while your baby is drinking, which at the end of the feed make the burp be so hard it sounds like it hurts) to go the back. The only setback on these bottles is that they don't close tight enough for you to mix (shake) formula in them. If you put boiling water on them, for example, they are not tight enough so the pressure in the bottle in combination with the tube brings the boiled water out and you can burn :). Cleaning them is also a bit of a mission, with the little scrub for the tube. But, again in my opinion, all that makes up for the difference it makes at the time of winding your baby.
We have and will use Dr. Browns.