Over the years I have purchased an embarrassingly large number of baby and toddler cups in the hopes that one day, one of them would not leak. (I’m sadly not kidding, we have a cupboard full of them.) ...

And we found that the best stainless steel option is the 12-ounce Thermos Funtainer Stainless Steel Water Bottle With Straw, and the best plastic model is the 14-ounce CamelBak Eddy+ Kids.