The Chicco KeyFit edged out the other seats because it came highly recommended by NICU nurses for premature infants. It has an excellent insert that offers extra support for such babies. All three have been through extensive crash testing and offer excellent safety features, like energy absorbent foam that offers extra protection in the event of an accident. The Combi Shuttle is an especially sturdy seat that you can install with or without the base without losing any of its safety features. The Britax BOB B-Safe also has a sturdy design and is extremely easy to use. This seat accommodates larger babies than the other two do, with its weight limit of 35 pounds.