Babies are extremely picky about what they will drink from and a rejected sippy is likely to become a missile. Even a well-loved sippy is likely to be banged and thrown around. According to experts and parents, it's practically impossible to get Dr. Brown's Training Cup (*MSRP $6) to leak. You can bang this cup on the table, play catch with it and "milk" the nipple without releasing a drop. The only catch is that the cup has many components to assemble, disassemble and clean -- and the cup's sip-activated drinking valve only works when you get this assembly right.
With a two-piece lid, another baby-favorite, the Nuk Learner Cup (*MSRP $7) is far easier to clean, according to parents. Also, some babies find it easier to hold and like the soft, wide nipple better -- although once they start teething they may bite it off, which limits its usable life. It's also not as impervious to leaks, but it does take some banging to get the liquid to spurt.
The bite-activated Born Free Training Cup (*MSRP $10) offers a free flow of liquid when the child bites down on the spout. This technology claims to discourage the pooling of liquids in the mouth that occurs when sucking from a bottle that can increase ear infections and lead to tooth decay in babies. The Born Free cup is not leakproof, and it doesn't claim to be. If you turn it over, water will seep from the spout, and if you squeeze the spout, water will pour out.
For the truly bold, the Baby Bjorn Cup (*MSRP $15) has an open lid cup and a wide, weighted base that is hard for babies to bump over. The cup is narrow and lightweight making it easy for little hands to pick up. This is the choice for parents who want to skip the sippy stage altogether, and they report that babies as young as 6 months old can drink successfully. But, carpets beware, babies can dump this cup. Luckily it only holds 3.4 ounces.