Our favorite and best options for baby bottles include glass, silicone, stainless steel and the safer plastic options. Things to consider when purchasing baby bottles are how many you will need in a 24 hour period, size of the bottle, whether you are using a breast pump and if your pump is compatible with the bottle you choose. When babies are 0-3 months a smaller 4 oz. size bottle works best, as it will be lighter and easier to hold, as babies grow 3+ months you will find the larger 8 or 9 oz. sizes are required for a single feeding.