A.,
I personally think the nipple matters more than the bottle. We use plain old Gerber glass bottles, but with their #1 nipples, and both of my sons have taken right to them. Make sure the flow is always #1!!! You want to make it as hard as possible for them to get the milk out. We never actually used above a #1 with my oldest. Make it a bit of a challenge, versus nursing.
I found that with some of the other nipples, you cannot always tell what flow they are. I really don't like the Medela nipples on their bottles. My 6 week old choked on them, but did fine with the Gerber nipples.
Good luck!
T.