I agree with the Nuby's. I don't have the flip top one, seeing as I just bought one a few days ago to try Lilie out with it, and she loves it. Doesn't seem to leak too much for me, and its a nice soft rubber straw for her to drink out of. For whatever reason she wont grasp the concept of taking a sippy cup and tipping it up to drink from it, so the straw was just easier to get her off the bottle all the time.