Water Street Seafood and Water Street Oyster Bar are virtually the same in menu, service, and quality. The Oyster Bar does have sushi but you can order from them if you are seated in the Seafood Co. Both restaurants are owned and operated by the same person/corporation.
The menu has some tried and true dishes that have been offered as long as I can remember, but they do change things up a bit from time to time. Sunday Brunch is good, but every meal I've had there is good.
I would suggest either restaurant for special occasions or just a night out.