Black Jersey Giants were bred for meat, and are fair egg layers. They were bred to be very large, and are also slow growing.
your other options, for dual purpose, are:
Any of the Rocks (Barred, white etc)
any of the Sussex (Columbian, Corination, Speckled etc)
Orpingtons, Buckeyes, Brahmas (another large, slow growing meat bird that also lays)