We got into the habit, as most people do, of using a particular brand of nipples/bottles. But that was more so that all the various pieces fit the other pieces. We had some random other bottles around and my sister once used one to feed the baby and it was fine. But the choice we ended up with was mostly about reducing gas.
In the very beginning we sometimes bought pre-mixed small bottles of formula, with disposable screw-on nipples. Those nipples are VERY fast and I came to hate them. It felt like putting a garden hose spewing formula into the baby's mouth.
Now that I'm trying to wean him off the bottle and he's on whole milk, I'm actually looking for a new bottle for him that doesn't use the "drop ins." And yeah, I'd like it to be as similar as possible to his former ones, though I suspect at this point it wouldn't matter as much.