Either the britax boulevard or decathlon, since they have infant inserts to hold a newborn snugly. Also, in case the baby is pretty small, Britax allows the straps to be an inch or so over the shoulders when the straps are on the bottom slots. If the baby is even shorter than that, you'll need an infant seat.
ETA: That's what I would use if I could do it over again. I hated the bucket with DS, but didn't realize it wasn't necessary.