We have tried dozens of sippy cups and straw cups in the past three years with our 2 kids, consistently, Gerber/NUK cups are the best. They have the same valve no matter what age group or style of cup, and all the lids fits all the cups no matter what the volume or age group. I've never had one leak and some of our first purchased cups have survived both kids are hardly look used. They are of course BPA-free and have tons of colors and styles available. The mix and match-ability of ALL Gerber/NUK cups makes our kitchen cabinet nice and neat: all the lids on one side of the shelf, all the cups on the other and all the valves in a little dish. Just grab one of each and you are good to go! The only complaint I have about certain cups are the ones that have no contours or curves: if they get slimy with food, they can be hard to grip to twist the lid off. That's actually a good thing with you have toddlers that have figured out how to take the lid off, but a slight inconvience to adults trying to clean the cups. Overall though, the best cups, hands down.
Powder Springs, GA