We bought the Playtex VentAire bottles and had great luck with those. I noticed that with the bottles we started out with (Avent), my baby had a lot of gas - this was both with breastmilk AND formula - so the bottle itself can make a big difference, not just what's inside the bottle. Anyway, they make all kinds of bottles that are supposed to reduce gas. The Playtex ones were not very expensive, which was why we tried those, and they worked out great for us.
If you can afford to do the pre-mixed formula, then of course that is a great option also. It's just a bit more pricey, which is why we didn't use it. I think you can mix your own formula and it can sit in the fridge for up to 24 hours, so that may be an option as well.