T.-
I am a midwife and have demo'd about a dozen different brands of pumps while teaching breastfeeding to nurses and to parents. I think you are right - the Medela pump has a tremendous amount of research behind it, and in practice seems to be the easiest to use, best customer service, and actually the best pump overall. Many of the other pumps are actually produced by parent companies that also sell formula, and as a consequence their commitment to successful breastfeeding is shallow at best. The reason that the quality of the pump matters so much is that since breastfeeding is mainly a supply & demand system, if the pump does not fully drain the breast of milk, then the message to the body becomes "Don't need so much, Make less milk." Medela is also careful to make their pump as strong as it can/needs to be, but yet with attention to not damaging breast tissue or nipples, always a plus! I've had both employees and clients have problems with their milk supply when they have used inexpensive or used pumps.
The bottle and nipple you choose to use is completely independent of the brand of pump, and is often dictated by the baby. It's not uncommon for parents to end up trying a couple different nipples and bottles, until they find the one the baby happily accepts. Its for this reason that I often to suggest to parents that once they've picked a bottle/nipple that they like, to just get one or two of them at the most, until they see how it goes with their little one before investing the number of bottles to meet their own particular needs. Make sure you get BPA-free bottles and nipples, BornFree and Adiri led the way with this several years ago long before it became a media issue.
All of these things, and some great advice, can be found at www.VisitIndigo.com.
Good Luck!
B