I have tried BARE (sample, not on the market when I got it), Platex Drop ins with latex nipple, Lansinoh mOmma, Avent Natural and Medela Calma.
BARE: Milk pouring everywhere just trying to tickle his lip
Playtex Drop in: Milk pouring everywhere ticking his lip. When he tried to drink from it (sitting up) he got flooded.
Lansinoh mOmma: Pretty good, first one he would take well, probably reminded him of nipple shield based on shape. He used these for the first two days I worked but would not go back to breast after two days (had to use nipple shields to get him back at all) so we quit those.
AVENT Natural: I put milk in and turned it up to test on arm, milk streamed out, not dripped, STREAMED. I didn't even offer it to him.
Medela Calma: Finally one that didn't flood his mouth (much) and didn't pour milk all over him. He doesn't seem to like it much, but he will drink from it. I am personally glad he doesn't like it THAT much, because he has had no problem going back and forth to breast.
BUT - at $18 per nipple/$20 for bottle with nipple, it's pricey. Really pricey. We have two and my caregiver washes it between uses for his three feedings.
I bought some Dr. Browns glass bottles because I planned to use just the bottle part with the Calma nipples, because I want glass bottles. Then I decided that people seem to really like Dr. Browns, and a really slow flow (preemie) nipple is available, so I went ahead and picked up some preemie nipples and we are going to try Dr. Browns this week. I can get 2 glass bottles with all parts and extra nipples (since I want preemie) for less than the cost of one nipple for the Calma. I hope they work...
ETA: Funny thing is, I have really fast flow boobs. I have overactive let down in one and it literally fire hoses him at first. Sometimes he spits it out and I soak it up with a burp cloth, but sometimes he just chugs it down...but fast flow nipples must be different than fast flow boobs...