I especially like the ones with straws, so you can drink while in a moving vehicle or while biking. I've tried so many brands. My last trip to the US, I bought 4 different kinds. My wife one time complained that I keep buying water bottles. But the truth is, they kept breaking, or leaking, or didn't really keep the water cold long enough, or it was just poorly designed.One day, my wife saw the Fifty Fifty Water bottle in a bazaar. She liked it. But because it was a bit on the expensive side, she had to bring me there so we could decide together. I was told it could keep water cold (or hot) for 24 hours. I was a bit skeptical, but decided we would give it a try.Wow, it really keeps the water cold for a long time! They are really well insulated, well built and well designed. As an engineer, I appreciate these things. Because we have two hyper boys, we've dropped the bottle many times already, Because they are made of stainless steel, they don't break. I think we've found the one! I'm sure my wife is also happy about that!